''Penn & Teller Tell A Lie'' is Creator/PennAndTeller's six-episode DiscoveryChannel show. The premise is that in each episode they will present six or seven outrageous claims, complete with video demonstrating them and experts explaining the science behind them, except that one of them (but only one) is a [[UnreliableExpositor big fat lie]]. The show challenges the viewer to try to spot the lie and vote on it live on Discovery.com as the show airs; then, at the end, [[TheReveal the lie is revealed]] along with the results of the vote.

Perhaps best summed up as ''Series/PennAndTellerBullshit'' [[XMeetsY meets]] ''Series/MythBusters''. The style of writing and presentation is very similar to ''Bullshit!'' (sensibly enough, considering they have the same writers, producers and presenters) aside from the milder rating, but the subject matter is uncannily ''[=MythBusters=]'' - they even inadvertently included stories in the first and six episodes that the [=MythBusters=] [[JustForFun/TropesExaminedByTheMythBusters had tackled before]].

For those wondering, [[spoiler:no, you can't stop a tiger attack with a punch to the gullet, nobody's ever used a jet engine to put out a forest fire, LaResistance never weaponized wine with yeast to make bombs, termites haven't caused a house to explode (yet - the science behind why it would happen is sound, and it is the cause of grain silo explosions), there is no such thing as a floating helium foam dessert, and magnets can't remove a tattoo.]]

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!!The show provides examples of:

* ArsonMurderAndJaywalking: In the hair story in the first episode, Penn starts off saying the hair is going to be lifting the car, followed by the weights of the people in the car, followed by the weight of the bowling balls placed in the trunk of the car, followed by the weights of the Oxford English Dictionary and camera that they're carrying, followed by the weights of other insignificant additional objects Teller brought with him into the car (including a bag of quarters and a CD of Meat Loaf's Bat Outta Hell album).
* TheBet: One of the stories in the second episode purports to be settling a bet between Penn and Teller about whether a match can be lit on the wing of an airplane in flight. When Teller apparently loses the bet (though he protests that since the plane was doing a hammerhead stall at the time it doesn't count as ''in flight''), he is forced to kiss a monkey. He incidentally does it while wearing a tutu, but according to Penn that wasn't part of the bet.
* BlatantLies: Though they do their best to make the false stories sound plausible, they employ this humourously a lot, such as when the narration pretends the "stunt doubles" of the first episode's plane story are actually Penn and Teller at the start.
* BraidsOfAction: The claim of the hair-lifting-a-Mustang story in the first episode is that simply braiding the hair makes it strong enough to hold up a car with three people (and a bunch of stuff) in it.
* BrownNote: One of the stories in the first episode involves alligators being turned on by a particular B-flat, which supposedly sounds like their mating call.
* ChirpingCrickets: Used humourously at one point in the airplane story in the first episode.
* ClusterBleepBomb: Used during and in the introduction of the pain-relieved-by-swearing story in the first episode.
* TheCoconutEffect: Lampshaded when Penn points out the sound used for a slow-mo shot of a bullet hitting a butter knife is completely fake, because sound in slow motion sounds terrible and "everyone loves the sound of breaking glass against a golf cart".
* CriminalMindGames: Penn and Teller intentionally leave hints that not all is right with the story that turns out to be false. For instance, the first episode's lie [[spoiler: was that tigers can be fought off by punching them in the gullet; it featured "security camera footage" from the zoo where the incident supposedly happened that randomly showed lion statues from in front of a library]].
* DramaticShattering: The revealing of the lie is punctuated by Penn and Teller smashing a glass pane with the false claim written on it with sledgehammers.
* InformedObscenity: One of the subjects of the "swearing helps relieve pain" story in the first episode uses what appears to be an eight-syllable swear word. As it is masked by bleeping, we don't hear it. Neither does Penn, to his dismay.
* ImportantHaircut: Johan gets his hair cut for science. (Or rather [[OnlyInItForTheMoney because he's unemployed and needs the money]].)
* LudicrousPrecision: Subverted in the hair story in the first episode - Penn starts rattling off the weights of not just the car and the people but also [[ArsonMurderAndJaywalking small objects Teller happens to be carrying]], making the viewer expect him to add together all the numbers he named, but then when he totals it all up, he just summarizes it as "four thousand three hundred and [[BlahBlahBlah blahdy-blah-blah-blah]] pounds".
* MythologyGag: In the climax of the piranha story, Teller is in a straitjacket on a platform over a tank full of piranhas while Penn reads a passage with Teddy Roosevelt's discussion of piranhas, with the platform supposed to drop when Penn finishes the passage. If you happen to have watched Penn and Teller in the eighties (or seen the appropriate Website/YouTube videos), you'll recognize this as a variation of a trick they used to do, 'Casey at the Bat', where Teller would hang upside-down in a straitjacket over a platform of steel spikes, struggling to escape before Penn finished reading the poem ''Casey at the Bat'' aloud (at which time he would jump from the chair he was on, which held the rope suspending Teller). Sadly, Teller is no longer able to hang upside-down for extended periods of time due to aging, so for ''Tell a Lie'' he had to do it right-side up, which isn't quite as dramatic.
* PantheraAwesome: The first episode has a story about how to fight off a tiger and makes a point of talking about how dangerous and powerful tigers are.
* PiranhaProblem: Featured in the third episode.
* {{Pixellation}}: Used on Penn's mouth during the ClusterBleepBomb (but curiously not on the subjects of the swearing experiment) and the copulating alligators in the B-flat story in the first episode.
* PropRecycling: Kind of. [[spoiler: In the first episode, the tiger story is the lie, and the tiger used to create the video was the same trained animal that appeared in ''Film/{{Gladiator}}''.]]
* RapunzelHair: Johan in the first episode, until Penn and Teller got their hands on him.
* TheReveal: At the end they reveal not only which story was a lie, but also how they hinted at it and how it was faked for the show.
* SelfProclaimedLiar: The premise is made clear from the beginning, and Penn's narration describing the stories repeatedly reminds the viewer that each story could just as well be faked.
* TheSilentBob: Teller, as always in their act.
* SpottingTheThread: As part of the premise of the show, the "lie" contains several hints that the story is not genuine, beyond the general premise. Just one example: [[spoiler:The story regarding using the jet engine to extinguish the forest fire is stated to happen near [[ArtisticLicenseGeography Laramie, the capital of Wyoming]]. As Penn reminds the audience after the "lie" is exposed, the capital of Wyoming is actually ''Cheyenne''.]]
* StuntDouble / TalentDouble: The airplane story in the first episode has two guys who look a little like Penn and Teller (one professional stuntman, one [[TalentDouble stunt pilot]]) fly the plane. At first Penn's narration hilariously [[BlatantLies pretends it's actually them]], but eventually he admits it's not and for the rest of the story they're referred to as Penn and Teller's stunt doubles.
* ThinkOfTheCensors: Frequently. During the alligator story in the first episode, Penn's narration wonders out loud how much alligator-sex Discovery is going to let them show, only to be disappointed as it is [[{{Pixellation}} pixelated]]. In the same episode, in the middle of the tiger story as they're about to cut to a commercial break, Penn suggests they wouldn't actually show a tiger eating a guy on Discovery, but then contends they might because it's animals.
* UnitConfusion: [[InvokedTrope Invoked]] in "Piranha Will Not Kill". [[spoiler:The yeast-based wine bottle bomb being fake was hinted when the generated pressure was given in ''joules''.]]
* UnreliableNarrator / UnreliableExpositor: They try to make you believe each story, including the lie. They also repeatedly point out that each story, including the true ones, could be false.
* TheVoiceless: Teller, of course, maintains character - though he has a fairly long audible argument with Penn in the second episode about whether an airplane in hammerhead stasis counts as "flying". It's just played over footage of the plane, so you don't actually ''see'' him speak. This is similar to various gags on ''[[Series/PennAndTellerBullshit Bullshit!]]'' where Teller also speaks off-screen.
* WhatCouldHaveBeen: During the filming of the "Piranha Will Not Kill" story, Teller casually had his feet in the piranha tank and one ''actually'' bit his toe. Supposedly [[HilarityEnsues hilarity ensued]], but although supposedly Penn and Teller asked the editors to put this part in the actual episode, they didn't.
* XMeetsY: If ''Series/PennAndTellerBullshit'' and ''Series/MythBusters'' had a baby, this would be it.

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