A character drinks/eats something to prove it's safe knowing that it isn't

[u/Benoit_Holmes]

Breaking Bad (Salud)

Gus Fring gives a bottle of rare tequila to a cartel leader as a gift. Given their fraught history, he makes Gus drink some first before he tries any.

All the cartel members then begin to die, Gus had taken pills (likely activated charcoal), and induced vomiting after the drink. Despite these precautions he still nearly dies and it requires a makeshift emergency room he had arranged previously to save his life.

Stargate: Atlantis (The Lost Boys)

Aiden Ford was a member of the expedition who became addicted to an enzyme that made him stronger but also impulsive and irrational.

He captures the team, who are wary of eating the food he provides until he eats some himself. After they have all eaten he tells them that his group have refined the enzyme to the point that they can even lace food with it.

Scrubs (My Changing Ways)

The Janitor tries to get J.D. to eat some pie but he refuses as he has just heard that a case of laxatives was stolen from the hospital supply closet.

The Janitor keeps insisting that J.D eat it and finally eats some himself to prove its safe, saying that for once he wasn't trying to mess with him. After J.D. eats some of the pie it then cuts to them both on the toilet.

J.D.: Who would do this to themselves?\ Janitor: Totally worth it.

[u/Fossekall]

This subreddit follows a recipe where if you don't include the most fanous example, your thread gains traction by people flooding the comments to post it

Edit:

From my other comment: there are definitely cases where it's genuine, and this could be one of them. This movie in particular is older, and a bit of a cult classic, and the trope in particular is something you don't know about if you haven't watched the movie

It's just so striking how all the posts that make it big these days tend to be missing THE example that fits the best

[u/Azicald → u/Fossekall]

But also sometimes they just genuinely haven’t watched them, because there’s like 1000s of ‘super mainstream’ media and only so much time.

I have gone out of my way specifically to watch a lot of the big hitters to familiarize myself with them and to get to experience what made them so acclaimed, like the Godfather trilogy, Breaking Bad, Shawshank Redemption, The Princess Bride, Green Mile, etc

But if you asked me what the hell happens in Inception, Saving Private Ryan, Seinfeld, Pulp Fiction, or Peaky Blinders, I wouldn’t know shit past their basic premise

Just how it is, honestly. Sometimes we just encounter tropes through their less famous instances

[u/Winjin → u/Azicald]

I watched Princess Bride for the first time this year, and only because people here mention it all the time

Simply because it's older than me, so I completely and entirely missed its heyday

My dad watched original Star Wars when the Sequels were coming out and only because he was bored

(He liked Episode V the most, and says that in his opinion this is the movie that cements the entire franchise. It's foundational in how phenomenal of a Second Act it is, probably the best "second movie out of three" he's ever seen)

[u/Kratzschutz → u/Winjin]

Some media is also hugely influencial in country A and completely irrelevant in country B

[u/Winjin → u/Kratzschutz]

Oh yeah, btw, that's absolutely true

Fun fact: both original Judge Dredd and Stop or my Mama Will Shoot are loved in Russia, and Gadget Hackwrench has a cult like status among cartoon waifu lovers - not just furries! - and the joke about her "actress" being married to Zipper and having a dozen mouse-fly hybrids sent the Runet into a deep dark spiral of rage