Two enemies are sharing a drink and one of the glasses contains a poison or drug. At least one of them will attempt to poison the other by switching glasses while the other's back is turned. Common joke is either that someone poisons a chalice, then they get switched over, or someone knows he's got a poisoned drink, and tries to find a chance to dispose of it without being obvious, or pretends to swap the glasses, waiting for the enemy to really swap them and drink. A common trick (most famously seen in The Princess Bride) is to poison both drinks with a substance that one is already immune to.
A less lethal variation is to shake up a bottle or can of soda or beer to release the carbonation and make it spray in their face when opened.
A Discredited Trope, more often parodied (or made fun of) than played straight these days. When switched and switched back, this is Two Rights Make a Wrong.
- An ident that ran on the Spanish horror channel Calle 13 implied this.
- A TV commercial announced that, on Mondays, a DVD with episodes of a British crime show would be included when you bought the Swedish evening paper Expressen. In the commercial, a British woman is preparing tea for herself and her husband, and secretly pours poison into his cup.
Husband: [Drinks his tea]
Wife (smiling): "I poisoned your tea..."
Husband (also smiling): "Darling, I know! I switched the cups."
Wife: "So did I."
Husband: [Gasps, and then promptly dies]
* The butler enters the room.*
Wife: "Bury him with the others, James."
- In an ITV ad representing the rivalry between drama and reality TV for viewers' attention, actor Jason Watkins invites Love Island star Kem Cetinay to his trailer, with the intention of killing him with cyanide in his wine. However, Cetinay, suspecting his intentions, asks if he has any nuts and swaps the glasses while Watkins' back is turned. Watkins realises this may have happened when he turns back to the table and that he now has no way of knowing which glass is poisoned, but he obviously can't admit what he did, so he takes an uncertain sip from one of them — which turns out to be the wrong one.
- Detective School Q: In order to trap the murderer who's planning to kill the last victim, they deliberately let him poison one of the coffee cups in a meeting with others. Then the detectives make an excuse so that everyone gets sent to another room. The coffee cups are then rearranged and re-served. Which one gets the poisoned one? Of course, the perp gets it, thanks to Megumi's photographic memory which remembers which cup is poisoned.
- The 17th chapter of Hunter × Hunter has this. Two candles, a long one and a short one will be lit. Gon has to predict which one will last the longer. Everyone instantly thinks this is a trap-in-a-trap-in-a-trap etc., but Gon obliviously chooses the long one, reasoning that it should last longer because of its size.
- The long candle is set to burn extra hot and extra fast, but this backfires because since the contest is to put out the flame, Gon is able to set the candle down unguarded and get his opponent's candle much more easily.
- It actually works out well for him in the end; he is correct. The real trick is that there are four candles: trapped short, trapped long, normal short, and normal long. Gon's opponent would give him the trapped candle with whatever one he chose, then picked the non-trapped version for himself. But since the contest was to see who's candle goes out first, he just blows on the other guy's normal candle and wins.
- Nakamura, a science teacher in Nichijou who's interested in Robot Girl Nano tries to see if she's susceptible to tranquilizers by giving her drugged coffee... only to realize too late that she'd poured and drank her own coffee after putting the tranquilizers in the pot. Later, she prepares this trick again, only for her adding the tranquilizers to make the coffee cup overflow. She instinctively leans forward to drink the excess off the top and... well...
- Unintentionally (probably) occurs in the movie of Revolutionary Girl Utena, where it turns out that Akio slipped a drug into his sister Anthy's drink, and when he thought she was unconscious proceeded to rape her, only to realize later that she was awake the entire time. He responds by stabbing her, and then falling out the window to his death due to losing his coordination from the effects of the drug.
- Done with notebooks instead of drinks, but the final Gambit Pileup in Death Note has a certain resemblance. Near proposed meeting Light and his team on a certain date and Light ordered his minion Mikami to meet them there and kill everyone in the room but him using his Death Note. Near expected this and replaced all the pages in the Death Note for that date and afterwards with ordinary paper, but Light had expected that and told Mikami to make a fake notebook and write in it where Near's agents could see him while Kiyomi wrote the names of the criminals he would normally kill on scraps of Death Note paper. But then Kiyomi got kidnapped by Mello and Mikami panicked and got the real Death Note out to dispose of her before she could reveal them all, allowing Near's people to find the real notebook and then replace it with another forgery. Then on the day of the meeting Mikami brought Near's fake thinking it was the real one and wrote in the names of everyone at the meeting except Light's, but since it was a fake they didn't die and he was caught and the fact that Light's name wasn't in the Death Note proved that he was Kira.
- Cowboy Bebop: A version of this occurs in "Cowboy Funk" when Spike and Andy are locked in an elevator by Teddy Bomber and are quickly ascending to the top of a building where a bomb will detonate and kill them. Andy says that they have nothing to worry about because he anticipated this possibility and reverted the emergency access code on the elevator after Teddy had changed it. Unfortunately for them, Spike had the same idea and also reverted it, so now it's back to what Teddy had changed it to in the first place.
- A Distant Soil: Colleen Doran uses this early on in her comic. Jason is offered some wine by the seemingly-kind Sere. He asks her to drink hers first, which she does. He then takes a few sips of his. One of Sere's servants then enters with a small metal tube, which Sere injects into her arm — it's the antidote. (Or inhibitor, or something—it's just drugged, not poisoned.) Cue Jason falling over.
- Batman (Grant Morrison): In a flashback in Batman R.I.P, we see Bruce Wayne drinking with a little Asian man in the Far East. The man then reveals that he poisoned Bruce's cup. However, the man himself begins to fall victim to the poison. Turns out, according to Bruce, "You blinked. I switched the cups. Force of habit."
- 2000 AD:
- Nikolai Dante: Played With. Nikolai and his half-sister Anastasia, who typically kills people by poisoning them are having a drink together. Nikolai's crest warns him that his glass may be poisoned, so he makes an obvious effort to switch the glasses, at which point Anastasia remarks that, as an experienced poisoner, she would expect a wary individual to try and switch glasses, so she would logically poison her own glass, instead. Then, when Dante switches glasses again, she remarks that since she's immune to her own poison, anyway, she would logically poison both glasses.
- Button Man: Harry agrees to let the person he is there to kill pour them both a drink, clearly expecting his drink to contain a sedative. So he switches the drinks and the other guy "accidentally" spills his, confirming Harry's suspicions. Then it turns out that both drinks were drugged, and the poisoner just spilled the drink to fool Harry into thinking the other one was safe. Of course he's also immune to his own drug.
- Alan Ford: The volume New Year's Party features a young, hot but greedy artist named Ramon planning to poison his older lover and source of income to inherit her goods, doing so by poisoning her champagne cup. Unfortunately, he had to leave the cups alone for a few moments, which lead to his bumbling sidekicks swapping the two chalices by mistake. In the end, Ramon ends up being forced to drink the poison by his lover at gunpoint, suffering a Karmic Death.
- The Far Side: In "When dumb animals attempt murder", a cat brings a dog a tray with two glasses of wine and loudly and pointedly states that there is no poison in the glass nearest to the dog.
- FoxTrot had a variation with salt in milk, between Jason and Peter with multiple switches and some alleged fake switches, culminating in the line "We're trying to figure out which of us should be throwing up right now." Turned out Paige had somehow gotten the salty milk.
- A Garfield strip has Jon Arbuckle suggesting that he and his date drink from each other's glasses... on the grounds that his last date tried to poison him.
- Spy vs. Spy:
- The very first cartoon in MAD magazine featured the black spy and white spy both subtly disposing of the tea they were supposed to be having by tipping it onto the floor. Two cats see the tea and lap it up, and are shown dead in the final panel.
- Another cartoon subverted it. One Spy had a ring they were using to poison the other spy's tea. The other Spy doesn't have to switch cups. Their own ring has a tiny fan that blows the poison into the first Spy's teacup while it's pouring.
- In Love with a Black Orion successfully switches cups during his wife Walburga's attempt to poison him.
- Subverted in the Fire Emblem: Three Houses fanfic A Chance for a New Dawn: When Bernadetta discovers that Monica has crashed a private tea party between her and Byleth, she immediately suspects her rival of trying to poison her. Bernadetta tricks Byleth and Monica into turning around so she can swap her cup with Monica's. She thinks she's succeeded when Monica has a violent coughing fit after drinking from her cup, only for Monica to complain that she drank from hers too quickly.
- Played with in the Disney film The Emperor's New Groove, Yzma tries to kill Kuzco by having his drink poisoned. During the meal, Kronk, the one to initially poison it, gets the drinks confused and ends up fixing his mistake by putting the drinks into a bowl, and then pouring it back into the cups, effectively putting the poison in all three cups. Kronk and Yzma pretend to drink theirs, but it turns out none of the drinks were poisoned in the first place — what he had put in them was a potion that changed Kuzco into a llama. A background gag has Yzma dispose of her drink into a nearby plant that becomes llama shaped.
- Inverted in Shrek 2, when Fiona's father the King brings two cups of tea into Fiona's room, one of which he had spiked with a Love Potion as part of a ploy to get her to marry Prince Charming. Fiona reaches for one cup, but the King says that he wants to drink that one (because it's "decaf"). Fiona obliges and drinks the cup that the King offered to her. At the movie's climax, it's revealed to the audience that the King had actually changed his mind at the last second, instead giving Fiona the untainted cup. The attentive viewer can catch that the king switched the cups after putting in the potion.
- Abbott and Costello:
- The duo sometimes did a variation: Lou gets a necklace from a mysterious woman, detective comes by and says a mysterious woman just stole a necklace, then Lou tries to hide it in Bud's hamburger so they don't get blamed for it. Eventually, Lou ends up eating it, just as the detective comes back and mentions there's a reward for it.
- In The Naughty Nineties, Costello's character ends up having a drink with a Femme Fatale. At one point Costello loses track of who has the poison, so he dumps it into a potted plant. That Poor Plant withers away and dies, prompting Costello to wipe his glass out very thoroughly.
- Happens to Lou again in Pardon My Sarong, when he and the island chief are having a "friendly" drink. Lou comes out on top of this one.
- Once more in Abbott and Costello Meet the Mummy, again with hamburgers, but this time with a cursed medallion.
- The Assassination Bureau: Ivan Dragomiloff sees the countess pour poison into his chalice. He spins both chalices on a rotating table and the countess refuses to drink since she does not know where the poison is. Dragomiloff drinks the non-poisoned wine and fakes death. 
- In The Awful Dr. Orloff, Wanda sees Orloff spiking her champagne in a Revealing Reflection. Playing Drunk, she asks him to buy her some flowers, then swaps their glasses while his back is turned.
- In the short film The Bloody Olive, Werner prevents poisoning by exchanging the glass of toxic champagne with a glass of sparkling water.
- Played for Laughs in the Czech film Císařův pekař - Pekařův císař (The Emperor and the Golem) - a group of conspirators attempt to poison Emperor Rudolf II. The plot is derailed when the chalices of wine - including the poisoned one - are used to demonstrate Copernicus' heliocentric system.
- Subverted in a terrifically cool way in the Hong Kong movie Color Of The Truth. Evil Mob Boss visits Hired Mooks in their hideout bearing celebratory bottles of wine. Head Hired Mook suspects this trope, so he demands that Evil Mob Boss takes a swig of the wine first - which he does. Evil Mob Boss leaves the Mooks to their party, then rushes out to a trailer truck parked a short distance away - in which a mobile medical unit is waiting to pump the poison out of his stomach.
- Confessions Of A Dangerous Mind had a fairly straight use of the trope. Patricia brings Chuck Barris a tray with two drinks; Chuck's is poisoned. She loses her attention for a moment, then comes back and notices the tray has been reversed. While Chuck isn't looking, she reverses it again. And she winds up choking to death on poison; Chuck hadn't reversed the tray, he just moved the objects on the tray around to make it look like he had.
- The Court Jester has an early parody of this trope, although it was trying to remember which cup was poisoned, rather than switching them. There is the truly brilliant rhyme they use to try and remember. "The pellet with the poison's in the flagon with the dragon! The vessel with the pestle has the brew that is true! But it's only in the flagon with the dragon because they broke the chalice from the palace.
- Played for Laughs in Daredevil (2003) when Foggy Nelson pranks Matt Murdock by handing him mustard instead of honey for his tea. As the supposedly-blind Matt has Super Senses he knows what Foggy has done and switches cups the moment Foggy turns his back.
- Although not involving poison, the alternate ending to Die Hard with a Vengeance plays with this trope. John McClane faces off with Simon Gruber, a rocket launcher with the sights removed on the table between them. They play the Simon Says game, with the rocket being turned each time Simon Gruber answers a question correctly. Eventually he gets a question wrong, so John tells him to pull the trigger. However, Simon turns the rocket launcher one more time before doing so, convinced the muzzle will then be facing towards John. He's wrong.
- In Heathers, Veronica mistakenly picks the wrong of two cups to give to Heather, who then dies from drinking the lethal potion.
- In The Hunger Games: Mockingjay Part 1, one of the secrets Finnick reveals about Snow is that his favorite method of disposing of rivals is through poison. Knowing they would expect this kind of treachery, he would drink from the same cup as them, but he had taken an antidote.
- In The Iron Mask Phillipe does this in full view of his mother. But since he's the king — actually, The Usurper who is impersonating the king — she has little choice but to drink it.
- In Kingsman: The Secret Service, Eggsy is offered a glass of brandy from Arthur. Having recognized treachery less than a minute before the offer is made (and already educated in the style of poison being used), Eggsy asks a question about a nearby painting as a distraction so that he can make the switch.
- At the end of The Little Girl Who Lives Down the Lane, as Rynn is making tea for herself and Frank, she puts potassium cyanide in her own cup. It's not clear if she anticipated that Frank would be suspicious and switch, or if she was initially intending to kill herself rather than submit to Frank's blackmail (and possibly framing him with her murder), or if it was a Xanatos Gambit (where, for the reasons stated earlier, either person dying would be a "win" for Rynn). Whatever the case, Frank becomes suspicious and demands that they switch cups, so he ends up dying.
- Love in the Villa: Charlie prepares dinner for himself and Julie to put an end to their prank war. Julie swaps their wine glasses just in case he put something in her drink. Charlie quotes the scene from The Princess Bride where Vizzini tries to psych out Wesley about which glass he'd poisoned and Julie swaps them back.
- In the 1938 German movie Napoleon ist an allem schuld ("It's All Napoleon's Fault"), Lord Cavershoot (Curt Goetz) and Lord Cunningham (Paul Henckels) spike one of the cups for afternoon tea with a delayed Mickey Finn so that the intended victim will be asleep and thus miss the big party in the evening. Unfortunately for them, while they aren't looking, Lady Cavershoot discovers an unsightly spot on the tablecloth, which Cunningham caused when he poured the potion into the tea. She doesn't know about the potion, but because she doesn't want the guest to face the spot, she quickly turns the table around, accidentally causing Lord Cunningham to drink the Mickey-laced tea.
- In Pirates of the Caribbean: On Stranger Tides, Jack Sparrow lies about which chalice contains the mermaid tear and thus will grant life, while the other one will drain life. Blackbeard values his own life more than that of his daughter, drinks the one he thinks will give life, and ends up dying.
- The Princess Bride features a subversion. After going through a long and increasingly incoherent I Know You Know I Know, Vizzini distracts the Man In Black and switches the goblets, then carefully waits for his opponent to drink first (since presumably the Man In Black would try to weasel out of drinking if he thought he was about to drink from the poisoned cup). Turns out the Man In Black poisoned both chalices, revealing to Buttercup afterward that he had built up a tolerance to the poison used. Ironically, both sides of his I Know You Know I Know were correct — "I cannot choose the wine in front of you" and "I cannot choose the wine in front of me" — even though he was only using them to fish for a reaction. Best of all, the Man in Black was playing fair — he never said his opponent had to choose a goblet, only that he had to drink. Vizzini could have avoided danger by refusing both goblets and drinking out of the bottle.
- Played with in Prince Valiant (1997). The villain spikes Princess Ilene's goblet with some kind of potion (love potion, sleeping potion... wasn't made clear). Ilene distracts him, switches goblets, and pours candle wax into his goblet. The villain gets suspicious and switches them back. He drinks first, and as he chokes on the wax, Ilene escapes.
- In the 1933 movie Roman Scandals, the Roman emperor's food taster (Eddie Cantor) is told "The one without the parsley is the one without the poison." But some busybody in the kitchen notices the missing parsley and puts it on.
- In Scott Pilgrim vs. The World, Scott pulls this: after the vegan bass player Todd bests him in a bass battle, Scott attempts to reconcile with him by offering a coffee with soy milk in it. However, as Todd has Psychic Powers as a result of his veganism (yeah, we know), he knows Scott's actually "poisoned" the cup with half-and-half, so he takes the one Scott is going to drink... but it turns out Scott offered him the one with soy milk and held the non-vegan cup close, and merely thought really hard about doing it the other way. The vegan police then come and take away Todd's powers for breaking the code (yeah, we know). An Adaptation Distillation from the comics, where Scott had nothing to do with Todd's downfall, beyond hoping for "some kind of... like... last minute, poorly-set-up deus ex machina". They still keep another element, though. It's not his first time to go against veganism...
- The Serpent and the Rainbow: After the first time, Dennis buys powder that's supposed to cause comas/serve as an anesthetic from Mozart and realizes that it’s rat poison, he palms the actual bottle with a different one which he pours into a glass and then drinks, alarming Mozart, before dismissing it as piss.
- In Sherlock, Jr., the detective played by Buster Keaton accepts a poisoned drink, then politely offers it to the would-be murderer's accomplice (who doesn't know about the poison).
- Stardust: This scene when the three remaining brothers, Primus, Tertius, and Septimus are having a toast to their quest for the magic ruby:
Bishop: To the new King of Stormhold. Whichever of you fine young men it might be.
[They acknowledge him and drink. The bishop's face contorts. Seconds later, he collapses, dead. The brothers look uncomprehendingly at their cups and then eye each other suspiciously. Tertius breaks the atmosphere with a laugh, which turns into wheezing, then starts having convulsions, and dies]
Septimus: [to Primus] You- [Clutches his throat and chokes on the poison. Seconds later, he falls on his back. Primus' eyes light up in realization at the fact that he is the only brother remaining. Thinking this means he is now the king, he picks up the crown reverently and is about to put it on when....]
Septimus: Ha-ha-ha-ha-ha-ha-ha! [stands up, laughing] You really thought you were king!
Primus: You killed the bishop.
Septimus: No, Primus, I think you'll find that you killed the bishop by drinking out of the wrong cup. [Primus looks crestfallen] Oh look, once you've finished wrestling with your conscience I suggest you return to your chamber. Leave the quest for the stone to me.
- In the book, all the brothers are savvy enough to only drink wine they themselves have poured from a sealed bottle. In the film, Primus refuses wine from Lamia at the inn, probably for that reason.
- The Survivalist has a variation: the poisoner gives the poison to the person that they intended, but the victim is probably not who the audience were expecting. Kathryn wants to kill The Survivalist and take over his patch. Her daughter Milja says that she will cook a meal with poison mushrooms. No one swaps their dishes around when the meal is eaten, but we find out that Milja gave the poison to Kathryn.
- The 2011 version of The Three Musketeers has a variation where it's the chalices themselves that were poisoned.
- Used in multiple The Three Stooges shorts. In one notable instance, Shemp and the villainess take turns distracting each other and swapping their wine glasses. The villainess, however, simply taps the glasses together when it's her turn, causing Shemp to swap the glasses around again and give himself the poison.
- The Woman in the Window features a variant. Alice slips poison into Heidt's drink, but he figures out what she's up to. After she offers the glass to him, he demands that she drink it instead. When she hesitates he smacks it out of her hand.
- War Room does this with dinner plates. When T.J. comes home to dinner with his wife Elizabeth after being on the business trip with the female associate (with Elizabeth knowing that her husband is having an affair with a female co-worker), he switches dinner plates with his wife, probably assuming that she put something in his plate that would poison him as some sort of retaliation or something. It is never explicitly stated why he does it.
- Once upon a time, an old man got tired of the neighbor kids mischievously stealing apples from his big apple tree. So he takes a sign, and writes on it: "One of those apples is poisoned!!!". He considers the matter done and goes to sleep. The next day, he finds a note attached to his big sign, which says, "Ha! Now there's two!"
- In the Benjamin January series, it's used to Shoot the Dog. There's no way to arrest a murderer without his revealing an extremely damaging secret, so Hannibal Sefton, who's a potential threat to the man, deliberately goes to have a drink with him and switches glasses when the man's back is turned. The murderer dies of his own poison and the secret is safe.
- In the Brother Cadfael novel The Potter's Field, a dying wife challenges her husband's mistress to a poisoned-chalice wager in which neither knows which glass of wine is drugged. If the wife dies, the mistress will have her husband all to herself; if the mistress dies, the wife swears to punish herself by refraining from taking herbal painkillers for her illness. The mistress agrees; by chance she's the one who dies, and the wife makes good on her promise.
- Agatha Christie:
- In the short story "Accident", a man suspects a woman of being a murderer. Before he can be certain, he must take a drink she offers him. He waits for her to drink first; she hesitates before pouring her drink into a plant. Confident he's beaten the switcheroo, he drinks from his vessel and promptly dies.
- The final Hercule Poirot novel, Curtain, contains two examples:
- 20th-century Iago Stephen Norton has manipulated Barbara Franklin into trying to poison her husband. While everyone else is looking at meteors, Hastings, completely unsuspecting, swivels the table around to get at a book, and Barbara drinks the poisoned coffee.
- In the second instance, Poirot tells Norton that he plans to kill him. Both are drinking hot chocolate, and Norton asks to swap cups. Poirot agrees, but he had dosed the pot of chocolate with sleeping tablets he had been taking for a long time (and thus developed a mild immunity to). Norton falls asleep, and Poirot later kills him.
- In Sparkling Cyanide, Iris Marle has a narrow escape from death: her handbag falls off the chair while everyone is away dancing, and a passing waiter who isn't serving this particular table and doesn't know who's sitting where puts it back up on the wrong chair. When Iris returns, she naturally goes to the place marked by the handbag. This results in Iris's brother-in-law getting killed and the murderers' plan going awry. Later, Anthony Browne demonstrates the mechanics of the accident with non-lethal (if very bad-tasting) substances: sitting in a café with two detectives, he lures them away from the table and moves the inspector's pipe from one cup to another. When the detectives return, one of them suddenly finds sugar in his tea and another finds out he's suddenly drinking coffee.
- In The Hollow, Poirot sees that the guilty party is trying to poison someone who knows too much, and switches the glasses so that the poisoner drinks the poison (and is thereby spared a public trial and execution).
- The G. K. Chesterton short story "The Bottomless Well" uses exactly the same variant as Curtain, with a revolving bookcase to accidentally switch the cups.
- In The Count of Monte Cristo, there is some in-story discussion of this trope as used by the Borgias. According to one of the men, the chalice contained a secret compartment that released the poison when the cup-filler needed, thus allowing him to serve an entire row of cardinals with only one in the middle one dying.
- Discworld, Mort: When Mort, who is subbing for Death, visits the Agatean Court, a poisoned piece of squishi goes back and forth between the vizier and the emperor's bowls as each thinks of a better reason for the other to eat it.
- Dream of the Red Chamber: Xia Jingui's attempt to poison Xiangling in revenge for inadvertently breaking up her potential tryst ends with Jingui taking the poison intended for Xiangling: The maid tasked with caring for Xiangling in her sickbed, feeling resentful at being made to serve a fellow maid, attempts to prank Xiangling by putting a large quantity of salt into her soup bowl. Upon witnessing Jingui, who prepares to drink the soup with Xiangling under the pretense of looking after her, swapping the bowls, and without knowing the bowl Jingui intends for Xiangling is poisoned, she secretly switches the bowls yet again to prevent Jingui from drinking the much-too-salty soup (and thus getting reprimanded for oversalting the soup). Accordingly Jingui falls victim to her own poison.
- Erast Fandorin, She Lover of Death: Accidentally. The chaos caused by Fandorin attempting to escape from the Trap Door causes Prospero to dive to the desk and close the hatch—causing the roulette wheel on which the two glasses are poised to spin around. That leads to Prospero drinking the glass of acid that he'd intended Horatio to drink.
- In Robin Hobb's Farseer trilogy, FitzChivalry ostensibly poisons his "victim"'s glass and gives him his own. He later takes a few sips of that unpoisoned glass, before noticing, a little too late, that the bottle had been poisoned by the Evil Prince. He barely survives, the victim doesn't.
- The Heroes of Olympus: In The Son of Neptune, Percy manages to pull this on Phineas with the gorgon blood. He wins. Doubles as Out-Gambitted.
- In Death: Non-lethal drug example. Whenever Eve goes too long without sleep in the middle of a case, Roarke will usually try to push food and sedatives on her. On one occasion, she switches their bowls of soup with a snarky comment and starts to eat — only to fall asleep. Roarke makes fun of her for it before she goes under.
- The Initiate Brother has a case where the cups are being switched by the poisoner so as to poison himself. Kogami Norimasa is given non-negotiable orders to poison Shuyun under the guise of sharing a drink, but because Shuyun cured his daughter, he wants to back out. Rather than let Shuyun drink the poison, he ensures that it's him who ends up with that cup, leaving Shuyun alive and himself beyond his master's retribution.
- Nation, by Terry Pratchett: Half-averted, half-subverted. In order to prevent two men from killing the islanders (and after they had already killed one), Daphne gets them alone and poisons them with undiluted beer. Foxlip, the one who had killed, does not switch the cups as per the trope, instead having Daphne mix the drinks together so they all get the same. Like Princess Bride, all the cups were poisoned. Unlike Princess Bride, it wasn't that Daphne was immune so much as understood the trick to make the beer safe: Spitting into the beer to neutralize the poison and singing the ritual beer song to count time it takes to work. Daphne did this right in front of the men and asked them to do it too, knowing that they would never partake in "pagan mumbo jumbo". As a result, Foxlip drank and died. The other man survived only because of continued suspicion but was sent running soon after.
- The Power of Five: Richard Cole executes this successfully in Oblivion with two identical cars, one of which contains a bomb, by not only switching a photograph and necklace from one vehicle to the other but also swapping the license plates.
- Used in Brian Jacques's Redwall novel Marlfox by Lantur, on her mother Silth. The mad old queen either overthinks it by several layers, or by one layer too few, depending on your point of view, on trying to figure out if her own royal goblet was poisoned or the plain pewter one intended for Lantur. She forces Lantur to drink from the pewter cup, but the poisoned one was indeed her own royal cup the entire time.
- It also occurs in Outcast of Redwall. Swartt convinces Bowfleg that the wine isn't poisoned by drinking some of it straight from the bottle. That's because the poison is actually smeared onto the rim of the goblet that Bowfleg drinks from. The trick is pulled at least once more and is later subverted by a fox who realized the trick (he's gotten rid of in a less direct way).
- In the Sherlock Holmes adventure A Study in Scarlet, the killer uses a variant to get revenge on the people who kidnapped his fiancee, without directly killing them. He corners each victim and produces two pills, forcing the victim to choose one and he agrees to take the other. The twist is that he deliberately has no idea which is poison but trusts in fate to punish the guilty. This breaks down when one victim refuses to pick (and instead attacks the perpetrator), forcing the killer to stab him.
- In the novel The Sherwood Ring, Barbara is taken prisoner by Peaceable, and lets him know (she can't hide it, really) that she's got sleeping drops on her person after hitting the apothecary that morning. After he starts to get a crush on her, and lets her know about it, she decides to pull the chalice switcheroo and hands him the red glass. He's well aware of what she's doing (especially since the cups are of different colors) and points out to her that he doesn't blame her for trying, it's just the general stupidity of her trying that irritates him. He switches goblets and challenges her to drink hers, she does, he does...then he says, "It was in the green glass all the time, wasn't it?" Yup. He'd informed Barbara earlier that all the girls he ever met in his life came off as fools and he assumed when she pulled out the goblets that she wasn't as smart as she appeared, and she took advantage of it. He promptly proposed marriage before he passed out.
- Invoked and played with in the French novel The Orange Trees of Versailles, the heroine learns the royal mistress is trying to poison the Queen and lets the king know. He decides to go the dramatic road and exchange his and the Queen's desserts, letting his mistress think she's actually poisoning him. "Luckily", he has her dog taste it first, and the animal dies in seconds, letting everyone believe someone tried to murder the king.
- A Song of Ice and Fire: In a dark Double Subversion of the "both chalices are poisoned" variation, Maester Cressen poisons a glass of wine, which he insists on sharing with his intended target, Melisandre, believing that she would not drink unless he drank as well and willing to die for his cause. She is fully aware of the ruse and tries to convince him to throw the wine away, but ultimately consents to share the drink with him. It turns out that she's magically immune to most forms of poison.
- Lux: Wingflare proposes a more complicated variant of this as a game for Jax and Paige. She presents them with three plates of licorice: One is laced with pine-nut extract (which is harmless to Jax or Paige, but which Wingflare is fatally allergic to and unable to regenerate from due to her weakness), one is laced with ricin (which will kill Jax or Paige, but which Wingflare can recover from with her gifted healing), and one is just licorice. Jax has to choose who will eat from which plate: does he give Wingflare the licorice with the pine-nuts and kill her at the cost of forcing himself or Paige to eat the licorice with the ricin and die of that, or does he give Wingflare the licorice with the ricin and let all three live. As Jax figures out, it's all a trick. All three plates are just licorice, and Wingflare isn't allergic to pine nuts.
- In 3rd Rock from the Sun, a reporter has to be Killed to Uphold the Masquerade. Dick pours two cups of brandy ("No thanks, I'm driving.", "Oh, this is special driving brandy.") and poisons one of them. Then Dick dramatically switches the cups around a number of times. After a Beat:
Dick: You look thirsty, why don't you drink both?
- The A-Team:
- Done in one episode involving a drugged hamburger, as they had knocked out BA before flying anywhere. Hannibal gave each person hamburger. BA got wise and switched burgers with Murdock, who take a couple of bites and collapsed. BA then eats the burger he took from him - and collapses. Murdock then "miraculously" revives and asks, "How did I do?"
- Another episode had BA once again switch hamburgers with Murdock, then figured Hannibal would suspect that and conclude the only safe hamburger would be the one he was originally given. BA still lost as it turned out Hannibal drugged his milk, not any of the burgers.
- The exact same gag as in Family Matters was also used in an early episode of Boy Meets World, with Stuart Minkus in place of Urkel and Shawn as the bully.
Shawn: Why do they think he's so much smarter than us? [takes a bite of "his" hamburger and winces in disgust]
Cory: Because he is, isn't he? [Shawn nods in agreement]
- El Chapulín Colorado: In one story, El Chapulin is helping two pirates to defect and a girl offers the Captain a cup of wine while El Chapulin is given a drink from a similar cup. Suspecting the Captain's wine to be poisoned, he and Chapulin keep playing switcheroo behind each other's backs until Chapulin pretends to switch and the Captain ends up drinking a sleeping potion.
- Chespirito has also done it in historical or mythical sketches.
- Columbo: Done in "Murder Under Glass", although the actual switch involved a bottle opener that had been used to inject poison into a bottle of wine. The killer watches Columbo sip his wine, and then smugly picks his own glass, only for Columbo to politely inform him that he wouldn't drink that if he was him. Columbo then explains about the switch, and how that glass full of poisoned wine will be enough to convict him.
- An episode of CSI does this, with peanut butter. (The intended victim was highly allergic.) The murderer changes her mind and takes the 'poisoned' cup but the victim ends up with it anyway. Just as well that what actually ended up killing him was a bee sting.
- The Dark Crystal: Age of Resistance has Brea do this when Elder Cadia puts a Laser-Guided Amnesia drug in her tea, claiming it's something that will help her understand her visions. Oddly, while Cadia only intended to wipe Brea's memory of the visions, he ends up forgetting everything.
- Doctor Who:
- "The Romans": Vicki overhears Nero's wife, Poppaea, plotting to have a servant poisoned. Feeling this cannot be allowed to happen, Vicki swaps the drinks over, meaning Nero will receive the poisoned one. When she casually tells the Doctor what she has done, he rebukes her for "interfering with history" and the pair hurry to stop Nero from drinking the poison. Though it's just as well Vicki swapped the drinks because, unknown to herself or the Doctor, the intended victim was Barbara.
- "Boom Town" (9th Doctor): The evil Margaret Blaine distracts the Doctor during dinner and slips poison into his drink. Then the Doctor, still smiling and without missing a beat, deliberately and in full view switches the glasses.
- Dracula (2013): A variation; the involved parties are both vampires and the "poison" is holy water. The exchange happens right in front of the poisoner who doesn't notice due to Dracula's fast reflexes.
- In Family Matters, Extraverted Nerd Steve Urkel sits next to a couple of bullies in the cafeteria, then has to leave the table for a moment. They sneak heavy amounts of salt into his lunch. Suspecting that they probably did something to his food, he uses a Look Over There ploy to make the bullies look away. They sarcastically play along, and Urkel picks the trays up and puts them down without switching them. They then use a Look Over There ploy themselves ("Look, it's Steven Hawking!"), which Urkel plays along with more convincingly, allowing them to switch the trays "back". Urkel then takes the "unpoisoned" tray and leaves before the boys bite into their salty lunch.
- Father Brown: Father Brown pulls this in "The Man in the Shadows" with a slight twist as he does it to save a life. Knowing that a Soviet agent has put cyanide in her tea so she won't be taken alive, he asks her for some sugar and then switches teacups with her while her back is turned.
- Frasier had a variant in one of their end-of-episode silent sketches. Roz brought some coffee to a woman she disliked but then got a call on her mobile; while she was distracted, the other woman switched the coffee. Then she got distracted, so Roz switched them back. This cycle of distraction and switching continued for some time until at the end, Roz just poured both cups down the sink.
- Get Smart:
- Max is dining out with a female KAOS agent. She is trying to give him a knockout pill, while Max is attempting to spike her drink with truth serum. Both of them keep pointing out things to look at behind the other's back, so they can switch drinks. It ends with Max telling everything he knows to the KAOS agent, who is fast asleep.
- Another case has Max doing this with Mary Jack Armstrong, both openly aware the other is doing it. Similar to the Family Matters example, she wins by distracting him and then not actually switching them, tricking him into switching them "back".
- Harry Enfield and Chums: One sketch has the Old Gits trying to kill each other. One tries to use poisoned cocoa; the other swaps the mugs. The would-be poisoner survives only because his mug broke as he was about to drink from it.
- House: Played almost-straight when House buys two coffees, grinding up amphetamines in one to give to Wilson. House offers the clean one to Wilson, who suspiciously declines House's offer and takes the drugged one from his desk.
- In I Love Lucy, Ricky tries to slip Lucy a sedative to calm her down, but Lucy thinks he's trying to poison and kill her, which leads to...
Lucy: I switched glasses!
Ricky: I know you did. I switched them back.
- In one episode of The IT Crowd, Douglas does this to himself. He is trying to drug Jen's tea, but gave himself tea in identical mugs, and switches the mugs around several times as he forgot which one is his. He eventually picks the right one though.
- The King Loves: Song In gives San and Dan two cups of tea, and says that one of them is poisoned. San pretends she'll give Dan the poisoned one, but she switches them when Song In looks away.
- Played quite straight in the German comedy Klimbim: 1st round, the heroine switches the chalices, 2nd round, the villainess switches the chalices, 3rd round, the heroine FEIGNS to switch the chalices, 4th round, the villainess switches the chalices. Glug Glug Glug. Hey, you should drop dead now. Drat. Since the villainess isn't completely stupid, she does NOT drink her glass but don't worry; she gets what she deserves eventually.
- Played straight in Merlin (2008) (except that they're both trying to get the 'poison', to save the other), up until the point that Arthur distracts Merlin to put both the 'poisoned' drink and the safe one in his own goblet. He drinks it, but there is actually no poison in it, just a sleeping potion.
- A recurring series of sketches on The Mitchell And Webb Situation was of a servant trying to poison his sick master. In one of them, the servant suspiciously suggests they should have drinks together and brings in two drink glasses on a rotating tray. But the master catches on quickly and starts spinning the tray around repeatedly until the servant loses track of the poisoned glass. The servant then decides that they should just have drinks later.
- Seen in a Morecambe and Wise Hamlet parody in which Eric and Ernie resort to ever more desperate measures to distract each other as they switch the poison chalice concluding with; Ernie: Look, there's a naked lady. Eric: Look there's an even nakeder lady.
- Murdoch Mysteries: Happens accidentally in "Prodigal Father": A person wronged in the past by a businessman attempted to poison him with a glass of liquor, unaware that the man never actually drinks alcohol: He merely keeps a glass in his hand to appear friendlier. Since the businessman doesn't actually care about the glass, at some point he set it down and later just picked a new glass up without really looking...
- In Police Squad!, a woman poisons one of two drinks. It works, but it looks like she drinks the one with the poison with it. This may have been on purpose; after all, the show is famous for never letting a moment go by without a joke, and packs tons of subtle jokes in-between the over-the-top sight gags.
- Power Rangers Lost Galaxy: In the episode "Stolen Beauty", Trakeena, after sending her Monster of the Week to Terra Venture to steal the beauty of all women, assumes the guise of a beautiful woman named Tracy and seduces Mike. When they get a drink, she poisons his. Mike drinks it, starts coughing, and collapses. However, it turns out Mike actually saw through the deception because earlier the Monster didn't attack Tracy. So he switched the drinks and only pretended it was working. He then throws the real poisoned drink in the monster's face, distracting him long enough for Mike to take back the stolen beauty.
- The Prisoner (1967): In "A Change of Mind", Number Six is made to believe that his aggressive behavior has been neutralized by ultrasound brain surgery — he comes to realize that it had been staged and that he's being kept passive with drugs, at which point he switches his drugged tea with a cup the scientist in charge is taking with him.
- Psychopath Diary: In-woo drugs Dong-sik's drink. Dong-sik hugs him then switches their glasses around while In-woo's distracted.
- Saturday Night Live: Steve Martin, always eager to protect his status as hosting the show more times than anybody else, once did a skit where he attempted to maintain his status by poisoning Alec Baldwin before he could tie the record, by slipping poison from his ring into Alec's whiskey. A series of switcharoos took place before Alec Baldwin pulled a fake switcharoo. Steve Martin, now suspecting that, decided to throw out the whiskey and order champagne, which he again poisoned. After another couple switcharoos, Alec resolved the issue by punching Steve in the jaw. Only then did Steve find out that this was only Baldwin's fifteenth time hosting, meaning he was still one short of tying Martin. Both of them felt very foolish.
- In Scrubs, Turk informs Dr. Kelso he's giving Carla regular coffee instead of decaf, due to her proclamation that the two of them will be going to bed at the same time, early. Dr. Kelso listens sympathetically, being an old hand at drugging one's spouse himself. Then, when Turk looks away, he switches Turk's decaf for Carla's caffeinated. Cut to: Turk awake all night as Carla slumbers.
Dr. Kelso: What a fun day...
- Done openly in the first episode of Sherlock, "A Study in Pink": the serial killer has two identical bottles of pills, one poisonous and one completely harmless, and forces his victims at gunpoint to choose one while he takes the other. The only "hint" he offers is to push one bottle closer to the victim, leaving them to try and work out if it's a bluff, a double bluff, etc. Sherlock realizes the gun is fake and is about to simply walk away, but the killer challenges him into playing anyway, playing on Sherlock's curiosity and need to show off his genius. However, before they can actually take the pills, Watson shoots him, and we never do find out which was which or if even the killer wasn't lying.
- Skithouse: The inviting host enters with one, and only one, glass of wine on a tray. He puts it down, lays a distraction, adds the poison, and he and his captive play out the distract-then turn scene, while the single glass is in the center of the tray and not moving at all. In the end, the host picks it up, and drinks.
- In The Two Ronnies serial "Done To Death", the two detectives suspect Blanche has poisoned their food. They both make several attempts to change their plates with hers; in the end, they both think they've succeeded and start eating, only for Blanche to remark innocently that she's got her original plate back. Fortunately, the food wasn't poisoned in the first place.
- Triple H did this with Shane McMahon when the latter drugged his water bottle so he would lose consciousness and would have no choice but to join Vince McMahon’s "Kiss My Ass" club. Remembering what happened to Shawn Michaels, Triple H got Shane distracted, and switched water bottles, so Shane drank the drugged water instead. Later that night, Triple H pulled a Wounded Gazelle Gambit on Vince and acted like he was under the influence of the drugged water. When Shane lost consciousness instead, Triple H got up and took down Vince with a pedigree.
- Clue VCR Mystery Game: This happens multiple times during the dinner scene. It reaches the point where no one ends up eating anything at dinner as no one is sure what has been poisoned and what hasn't. If one pays close attention, the viewer can find one serving on the table that isn't poisoned, but only because the first person to start serving food served himself before trying to poison everyone else's helpings.
- Older Than Steam: William Shakespeare did it in Hamlet. Specifically, it was done with swords. Laertes cut Hamlet with a poisoned sword in a fencing match, and in the ensuing scuffle, Hamlet took Laertes' sword and cut him as well. In the exact same scene, Gertrude (accidentally or not, depending on the director) drinks the poisoned wine Claudius meant to use on Hamlet if the sword trick failed.
- Bullshot Crummond. Bullshot suggests one last drink before Count Otto von Bruno kills him off, and slips knockout pills into his glass. First he hides the doped glass and holds out the other to Otto, knowing he'll insist on swopping. Otto takes a sip and spits it out, then suggests they drink "Eastern European fashion" so Bullshot gets the doped glass. Both end up keeling over.
- In Margin for Error, the suggested explanation for the Consul dying of a glass of cyanide-poisoned whiskey when his own drink was brandy is that Max, who was being set up to commit suicide, switched the glasses during the confusion after the brick crashed through the window.
- In Discworld, you poisoned someone with a truth serum, and both characters distracted each other with pictures in the inn while switching the table. You had to create a new picture to get your opponent to drink it.
- In Suikoden II, the King gets poisoned not because there was poison in the cup or the wine given to him by Jowy; but because Jowy had poisoned himself before he symbolically bled himself into the wine to symbolize his loyalty. He then took a lot of antidote, but still almost died.
- This comes up in party banter in the Dragon Age II Mark of the Assassin DLC. Varric mentions a relative who tried to do this but was very bad at intrigue. "Wasn't finished gloating to his enemy when he keeled over. I think the family always had a sense for terrible drama."
- Kingdom of Loathing:
- At the end of the 'Strange Leaflet' sidequest, you meet a giant who offers you two shot-glasses of potion; he tells you that one is poisoned and if you drink the safe one, he'll take you to fairyland. It's a Shout-Out to Ender's Game — as in the original, the giant is lying, both potions are poison, and you have to Take a Third Option to solve the puzzle.
- An early 2014 revamp to the Holy Macguffin quest involves an alternate route to get the two halves of the Talisman 'O Nam. Crime lord Shen Copperhead keeps poisoning you into getting various artifacts for him and one attempt involves him switching around poisoned glasses of champagne.
- In Dishonored, you come across one of your assassination targets just as he's about to poison a political enemy. You can then switch their glasses and have the target drink his own poisonnote , mix the drinks and poison them bothnote , or smash both glasses and force your target to carry out his assassination the hard waynote .
- In Kings Quest (2015) Episode 1, the final challenge is a battle of wits against Graham's fellow Knight candidate Manny, playing a chess-like game with the added caveat of three goblets of raisin juice, one of which has been drugged with a Truth Serum-like potion. Subverted in that while you can switch the goblets, it doesn't do any good; you'll always end up drinking the potion. The real solution is to use the recoloring potion you got earlier in the game to mark the poisoned goblet (turning the raisin juice orange, which Manny somehow fails to notice). This is just one of many Actor Allusions to The Princess Bride since Manny is voiced by Wallace Shawn.
- Depending on player option, this can happen in Life Is Strange: Before the Storm. Before The Tempest, Victoria puts some drugs into Rachel's tea, so that she can play her role instead. Chloe has several options to prevent this, one is switching the cups. Hilarity Ensues when Victoria tries to persuade Mr. Keaton to let her play the role instead, with the pretext that Rachel is taking drugs, all while visibly out of balance. Then, she promptly passes out.
- Sorcery!: A witch who offers the Analander a drink actually poisoned her own cup to test their trust. If you don't switch the cups, she poisons herself, staggers out of the room to grab the antidote, and then comes back to talk business.
- Sunless Skies: During the last event for the Amicable Vagabond, he attempts to trick you into drinking a drought that will get you sucked into Old Tom's Well for all eternity. If you switch the glasses when he isn't looking, he accidentally marks himself for the ritual, and no matter what happens next, he doesn't get out intact.
- The James Bond parody in Concession mocked this trope:
- In Oglaf, the obviously gay Xoan ambassador who is friends with the Apprentice's Mistress offers the Apprentice poisoned food claiming it's all the rage and pours the antidote over his penis in hopes that the apprentice will have to suck it off. The Apprentice says he's going to his room to write a letter to the Mistress saying the Xoan ambassador murdered him. However, when the Ambassador tries to turn it into a mystery drama, including offering a locket with the ambassador's picture inside (which he has a bag of), the apprentice says he doesn't believe it was poison. Later the Mistress calls the Apprentice in to punish him for being in the room that the ambassador had called him to; only for him to collapse from poison causing the ambassador to yell "He's been poisoned!". Later still, when he's sent to be cured in a painfully disturbing way, the ambassador reveals the Apprentice made a smart move because the antidote was poison as well.
- In Disenchantment, we learn that Bean's mother Queen Dagmar was petrified by a glass of poisoned wine meant for her husband, but Bean, then a baby, was playfully turning the serving tray around. Then, after she's un-petrified, it turns out she was the one who poisoned the wine.
- A three-way version on Johnny Test: In the Brain Freezer's first appearance, Johnny and Dukey disguise themselves as baristas and offer to share some iced coffee with him, with the coffee intended for Brain Freezer being his own super-cold coffee that freezes the drinker solid. He sees through their ruse and Dukey ends up drinking the spiked coffee instead.
- In an episode of Klondike Kat, he is trying to drug Savoir-Faire, who knows what he's trying to do. They keep switching the glasses around until Savoir just clinks the glasses together once, but leaves them as is. Klondike switches the glasses again and winds up with the wrong glass.
- Done in the Looney Tunes short "The Fair-Haired Hare", where Bugs and Yosemite Sam keep swapping drinks. Bugs eventually starts the whole table spinning. Sam stops the table and forces Bugs to drink at gunpoint. He still gets the wrong glass.
- Popeye: One story features Popeye and Brutus as rival farmers trying to win a competition. One of the events is the tastiest hamburger contest and Brutus sprinkles Popeye's burger with red hot pepper. Popeye and Brutus constantly swap burgers behind each other's back until Popeye outsmarts Brutus by pretending to swap burgers.
- Star Wars: The Clone Wars: In "Dooku Captured", Obi-Wan and Anakin use the Force to pull this trick off on a gang of pirates. But then they get knocked out anyway between episodes because the lead pirate's pet sees them and uses a gas to knock out everyone.
- A rumor to the origins of toasting is thought to contain this trope. It was more a sign of trust (similar to handing someone a weapon with the business end pointed at yourself) that your drinks could accidentally slosh and mix, and both men would come out of it in good health. Whether it is Truth in Television or not is heavily debated.
- Rapists like to add drugs, commonly called "roofies", to an unsuspecting victim's drink to facilitate the rape. This trope occurs when someone notices the attempt (either the victim or a bystander) and swaps the drinks, causing the rapist to drug themselves accidentally. When this occurs, the rape is prevented, and most people hail the person who swapped the drinks as a hero.