Smartest joke in a dumb movie?

I love it when a movie has some really dumb humour, but some deceptively smart jokes as well. Usually tends to show how good "dumb jokes" can only be written by outstandingly smart writers. Example: "La Cité de la Peur" (1994) is one of the most iconic French comedies. It has a lot of dumb, crass, surreal jokes in it, on par with movies like Airplane! or The Naked Gun. It's also full of references to the movie industry. At some point, we see a crowded, agitated theater at the Cannes festival, and all the attendees shout the word "brouhaha" in unison again and again. My teenage brain didn't think much of it, until years later when I learned that, on french movie sets at least, to make a crowd sound like blurry conversations without having to write any lines, directors used to have everyone say "brouhaha" over and over again (out of sync obviously). Mind blown. What are some of your favourite smart jokes in movies that could be seen as dumb?