This is often done to imply that the character in question either didn't trust the food, or in the case of the Picky Eater, just might not expect it to taste good, wherein seeing someone else eat the same thing was enough to change their mind.
Of course, part of the problem with this is that just because some food is good for one creature doesn't mean it will be good for another; among those who take this into account even this approach might not be enough to convince them.
Another variation on this trope would be "so good, the taster eats everything." This is used more in commercials, where a parent might eat the whole jar of baby food instead of serving the child as they started.
- In one Baby Blues strip, Darryl tries to get Zoe to eat her baby food by tasting it. After taking a moment to sample it, he starts eating out of the jar and gives Zoe his hamburger.
- And in a Hi and Lois strip, Lois demonstrates how to eat with a spoon when the baby tries to put the food in her ear. Then the baby demonstrates she has learned - by putting the spoon in Lois' mouth!
- A variant on the baby-food version crops up in My Golden Sun/Kin-Kur Lashark Tnash-Veh. After utterly failing to convince his daughter to eat, Jim decides to combine this trope with Reverse Psychology...only to realize that the food is absolutely disgusting and that T'Aman was right to refuse it.
Jim: And this won the 'Baby Food of the Year' award?! It's worse than the vege lasagna in the Academy cafeteria!
- In Dolphin Tale, wherein all the more qualified aquatic life hospital employees don't know how to convince Winter to drink from the bottle she needs to drink from, newcomer Sawyer comes up with the idea to drink from it himself in front of her. As seen in the page image, it works.
- Free Willy has a variant of this. Jesse tries throwing Willy the fish and it doesn't work, so he holds it up and pantomimes eating it. This leads to him eventually realizing Willy wants him to put the fish right into his mouth.
- In Hellboy, Professor Trevor Bruttenholm tries to coax baby Hellboy to him with a Baby Ruth candy bar. He takes a bite first to show Hellboy that it's food and offers him the rest. Hellboy accepts the bar and by extension the Professor.
- This is how Rell persuades the titular kitten to drink from a saucer of milk in Keanu.
- In some versions of the Snow White fairy tale, the wicked queen has poisoned only half of the apple, and to show Snow White that it is perfectly safe to eat, takes a bite from the side without the poison.
- Finding Bigfoot. James "Bobo" Fay once cooked up some bacon because he believes that "squatches" like the smell. He said that after the bacon was cooked he would throw pieces of it into the woods for them to eat, and he ate some to show any that were watching him that it was O.K. to eat it.
- House: Dr. House uses a similar tactic to get a low-functioning autistic kid to put on an oxygen mask. He refers to it as "eating the yellow berries".
- Malcolm in the Middle: Dewey is given the task of feeding a very reluctant Jamie. To get him to eat, he eats a spoonful of the baby food. As it happens, baby food is apparently delicious, and Dewey spends the rest of the episode eating tons of baby food, along with wearing a onesy and diapers...
- Mark Briscoe has been seen eating bird food before feeding it to the chicken and other birds on his farm. However, he's also been seen eating any excess bird food they don't eat.
- In Final Fantasy V, one of the protagonists ate dragon-grass (which is poisonous to humans) to encourage an injured dragon to eat it (to heal the dragon's injuries).
- An episode of The Flintstones has Wilma telling Fred to help Pebbles eat her mush, since she says that "she always eats it when he's around". Naturally, the "taster eats it all" routine ensues.
- Little Princess: In "I Want Baked Beans", the Princess wants to eat baked beans instead of the pasta she's supposed to be eating, so one of the adults tries to "show her how" and ends up eating it all.
- Max and Ruby: In "Max's Breakfast", Ruby tries eating some of the egg to show Max that it is good. However, she ends up eating it all.
- My Little Pony: Friendship Is Magic:
- In "A Bird in the Hoof", Fluttershy put her mouth into a soup bowl, pretending to sip it so that Philomena would do so as well. It doesn't work.
- Pinkie Pie tries this on Pound Cake and Pumpkin Cake in "Baby Cakes".
- The Simpsons:
- Homer ends up doing the "taster eats it all" variant with Maggie's food. When he finishes it off, the camera reveals about a dozen other empty jars he'd already eaten offscreen.
- Similar example came from Bart trying to get a cow to eat grass. He eventually started hogging all the grass.
- This method of feeding is attempted by animals. An underwater photographer had a close encounter with a leopard seal. The dangerous predator thought the photographer was a weak baby that didn't know how to eat, and provided assistance by giving weaker penguins, eventually dead ones, and showing the photographer how to eat half a penguin.
- It also works with humans. Anyone who's ever been a mother, a father, or otherwise around small children knows that the best food is always on your plate, not the child's plate. Placing something on your own plate and eating a bite, then offering the child a bite, can convince them to take foods they might otherwise refuse. This is likely an inborn instinct: infants don't know what is and isn't good to eat, but their caregiver likely does, so eating exactly the thing they're eating (not just something that looks like it but is in a different place; the exact thing) is a good way to ensure your food is safe and tasty.
- Begging dogs as well. Stick the lettuce in with the kibble? Blah, that's what food eats! Stick the lettuce on your plate and "accidentally" drop it under the table? BEST FOOD EVER! Like the children above, they might just develop a new favorite.
- This is precisely how many wild mammals learn what to eat and what to avoid ingesting: they watch their mothers eat.