What's the funniest scene you've ever seen in a movie?

The Heartbreak Kid/"I want out of the marriage!" scene is so great in how it starts out with Jeannie Berlin oblivious and Grodin dying inside while he tries to get his point across, and then when she realizes what's happening it switches to him being oblivious and her dying inside (and of course he perks up once he has the chance to get into his sales pitch about why this is actually a good thing for both of them), like she's contingently oblivious where he's essentially oblivious

this line always makes me laugh, the fact that it was apparently improvised makes it even better

https://www.youtube.com/watch?v=NhdNT1dnoL8