In which a character touches a blood stain with his fingers, usually in order to make sure that it actually is blood.
Sometimes, it turns out to be ketchup or strawberry jam (something that's red, goopy and fake), especially if another character has been doing a Chicken Little impersonation over the supposed bloodstain. Being a vampire or a cyborg may also help for analysing the type of blood. In Real Life, it's possible that some animals (bloodhounds, brown bears, tyrannosaurs, larger sharks) may have a sufficiently powerful sense of smell, this (or simply sniffing the blood) might actually allow them to determine the species or even the individual victim involved.
- The title character of Inuyasha is half-youkai and has the supernaturally sensitive and accurate canine sense of smell to show for it, with the result that he's frequently shown noticing the scent of blood over considerable distances, and can recognize when the blood belongs to someone he knows personally.
- In Pleasant Goat and Big Big Wolf: Mighty Little Defenders episode 1, the wolves are hurt and have what appears to be blood on them. Wolffy tastes the blood to make sure it's actually blood, and then he says it's just tomato sauce.
- Caballistics, Inc.: During the mission at the Luddgate studio, Hannah tastes some of the blood the team finds all over the floor. It's not real, being merely Kensington Gore, but the blood itself is drippling down from mid-air.
- In a Marvel Comics Dracula story set during World War II, Dracula identifies a bloodstain as "gypsy blood" this way. Well, he is a vampire... (Nazi troops were killing Roma. The Roma in Transylvania are protected by Dracula. Bad Move.)
- Lehrigen, a human from the Wild Hunt subseries of ElfQuest, is an expert hunter and tracker, and can tell human and elfin blood apart by smell and/or taste.
- In the prequel to Dragon Age: The Crown of Thorns, the middle Aeducan child sends a red-soaked nug into a feast full of dwarven nobility. After mayhem ensues, the visiting King Maric tries some and announces it's cherry jam.
- In The Keening Blade (Dragon Age: Origins) the slightly-mad Maude samples the bloodstains available in Warden's Keep:
"Walking dead and raspberry jam?" Maude complained. "There's raspberry jam on the votive candles! What kind of chapel is smeared with raspberry jam?""What kind of chapel is full of mindless zombies?" Loghain wondered, laying another one low."All chapels," Morrigan shot back. "And that looks like blood to me. How do you know it's raspberry jam?""I tasted it," the girl replied loftily, finishing off the last of the monsters. "It's not blood, it's raspberry jam. I checked."Kicking a skeleton aside, Loghain snarled at her. "Didn't your parents ever teach you not to put strange red substances in your mouth?" He thought again. "Or any strange substances?""I know about mushrooms," she replied. "I'm not an idiot, you know."
- And there actually is an inexplicable jar of jam to be found in-game.
- Actually somewhat justified in Cornered!, since a lot of shelves were knocked over, and it could have very well been ketchup.
- Played with in the "Thanksgiving" trailer in Grindhouse, when two small-town detectives are investigating a murder scene amid the titular holiday parade. And by "investigating a murder scene" we mean, "The headless body is right there and the blood is still leaking out of it".
Cop 1: (Touches, then tastes) "It's blood." Cop 2: "Son-of-a-bitch!"
- Dumbledore in Harry Potter and the Half-Blood Prince. "Dragon blood."
- Loaded Weapon 1 has an example where it's ketchup, given it's a parody.
- Gimli tops it by tasting the orc blood in Peter Jackson's rendition of The Lord of the Rings. While this raises the question of how he even knows the difference to begin with, the fact that he immediately spits it out in disgust suggests he's familiar with its repulsive taste. Given that he hacks orcs apart with an axe, its perfectly reasonable to assume that hes been sprayed in the face with orc blood before.
- The 2001 obscure Nickelodeon movie, Snow Day, had the elementary students try to derail the snowplow man's efforts to remove the snow from the streets since it will reopen their snowed-in school. One of their less successful methods was having one of the students lie in the middle of the street in wait of the snowplow man with ketchup on his shirt pretending to be unconscious. Bemused, the snowplow man simply stands next to the boy, dipping his frenchfries in the ketchup and eating them.
- Star Trek VI: The Undiscovered Country: Chekov finds a dried drop of something pink on the transporter pad, and pokes it before taking a sample. It's Klingon blood, which is what he was looking for.
- Repeated in the director's cut, with Colonel Worf investigating the pool of blood surrounding the attempted Klingon assassin.
- Terminator 3: Rise of the Machines: This is how the T-X can determine the identity of her victims if there is ever any doubt. (DNA scanners in her tongue. Who'd have thought it?)
- In Chris Jericho's autobiography A Lion's Tale, he describes a Ketchup Test incident that occurred during one of his early matches. Jericho bled a lot in this match and one of the ringside fans, believing Jericho's real blood to be ketchup, dipped his finger in a pool of Jericho's blood and put it in his mouth.
- In Robert A. Heinlein's To Sail Beyond the Sunset, the protagonist wakes up in a strange hotel room with a dead body in a pool of blood. After she phones for help, two doctors arrive. They each dip a finger in the "blood" and taste it. As she is feeling rather sickened, they begin arguing over whether it is Heinz or Skinners brand ketchup.
- In an episode of Beastmaster, Dar sees a spilled blue fluid and dips the tip of his spear in it so he can examine it without having to crouch. It turns out to be unicorn blood, and the blood on the spear makes it child's play for an Evil Chancellor to frame him for attacking the unicorns.
- In an episode of Bones, a street sweeper mulches up the body of the episode, one of the drivers assumes he's being pranked and tastes the "fake" blood to try to determine its contents. His partner vomits.
- Series/Bunkd: In "Inn Trouble", after seeing Finn licking the "dirt" off of his arm, Gwen reaches over and puts her finger into the "blood" on his elbow and tastes it, recognizing it as raspberry jam. Lampshaded by Destiny who asked her what if it had been blood.
- Chappelle's Show: Dave Chappelle explains that since semen is also a tool used by police to frame the black guy while doing their jobs, they might check that instead.
- Inverted in Community. Britta sees a red stain on Jeff's shirt and is afraid it's paint. But with a relieved sigh he realizes that it's just blood.
- Though it wasn't blood that he tested it with, Gil Grissom did this twice in CSI. The first time, Brass merely stared in horror at him; the second, Catherine warned him how unsanitary it was.
- Doctor Who: In "The Christmas Invasion", the Doctor does this. He then tastes the blood and identifies it as "A-positive, with just a dash of iron" (although his Bizarre Alien Biology could let him do this).
- In an episode of Fringe, the ketchup test is notably averted. The team finds a reddish stain on a piece of evidence left at a kidnapping scene, believing it at first to be blood, but they bag it and submit it for analysis only to discover that it is not blood but hot sauce.
- Walter has a recurring habit of tasting whatever disgusting thing they're dealing with and then revealing it's just some food he left lying around in the lab. He's done this with what appeared to be blood, brain matter, and cremated ashes. Taste is apparently the most important sense for scientists.
- Given that, the hot sauce example seems particularly notable, since it would be a perfect specimen for Walter's Sniff Sniff Nom antics, since hot sauce generally has a distinctive odor.
- In a sketch in Horrible Histories, Viking Paramedics know it's blood already. They taste it because they believe they can figure out what's wrong with the patient by doing so. They can't. This sketch is accompanied by the most, if not the only, truly serious Don't Try This at Home warning on the show.
- The X-Files, episode "Revelations": Mulder dabs his finger in "blood" and licks it. He promptly informs Scully that it has too much sugar. The look on Scully's face...
- In Idiotsitter, during the episode "Fight Day", Gene surprises Billie in a dark garage, and paint cans fall on her. Hours later when Billie wakes up, she's got red all over her shirt and screams, before she realizes it's paint.
- "Last Christmas!", a Season 2 episode of DuckTales (2017), saw Dewey Duck go back in time to meet his uncle Donald and mother Della, back when they were kids. He and Donald go looking for Della who has gone camping in the huge expanse that is Uncle Scrooge's backyard, and they come across a reddish substance smeared on a tree. Without hesitation, young Donald walks up, takes a huge lick of the unknown substance off the tree.
Young Donald: Yep- strawberry jam!Dewey: What would you have done if it weren't?