Hilarious in Flashback

A flashback occurs where the character mentions something that is only funny due to the irony of how it conflicts with their present character. For example, Alice is an expert chess player and Bob is always looking for work. A flashback has Alice telling Bob she's considering taking up chess but doubts it's her game, and Bob expresses optimism over being able to find a new job quickly.

Compare Hilarious in Hindsight, which is the non-in universe version of this Trope.

See also Irony, Futureshadowing and It Will Never Catch On.

Anime and Manga

 * Yu-Gi-Oh, Grandpa Muto makes a vow in a flashback that if he ever loses a game, he'll give up adventuring, open a game shop and wear overalls for the rest of his life.

Live Action TV

 * Frasier, a flashback shows Martin has a pet goldfish named Eddie. His partner tells him to consider a "real" pet like a dog, but Martin says he isn't a dog person.
 * The Big Bang Theory, when Leonard moves in Sheldon puts in the roommate agreement that they will set aside time to watch Firefly, "we may as well get it out of the way, it's going to be on forever".

Web Original
""Not sure what this is. Something about a cheerleader? I'm sure there's something about it in a couple places on the Internet. I think there was a 1992 film by the same name, and then the guy who wrote it didn't like how it turned out and made it as a series instead.....who knows how it'll go. Maybe the geeks will get into it?""
 * Platypus Comix used this in "The Lost Art Of TV Guide Advertising: Spring 1997". One of the ads shown was for the series premire of Buffy the Vampire Slayer, and it was annotated with this: