No single favorite, but some of my favorites:
The hysterical lady on the plane in the movie Airplane.
Naked Gun movie when Leslie Nielsen discovers Anna Nicole Smith is really a man and then throws up in the tuba.
About 20 scenes from Mel Brooks movies. A few examples:
- The "black sheriff" riding into the town of Rockridge in Blazing Saddles
- The brothers combing the desert in Spaceballs
- Gregory Hines trying to prove he is a eunuch and failing in History of the World Part I
- The Inquisition song in History of the World Part I
- The castle getting repossessed in Robin Hood Men in Tights and Blinkin is introduced to Achoo (Dave Chappelle) and says "A Jew? . . . Here?"
Many others.