Duck Soup, A Night at the Opera, and A Day at the Races---the Marx Brothers' three best films. (someone's gonna mention Horse Feathers and Animal Crackers, and I'm not going to dispute their valid points, but those are my three. Hell, watch those too.)
Monty Python...and the Holy Grail, Life of Brian, And Now For Something Completely Different, and Meaning of Life.
Slap Shot and Major League for funny sports movies.
Or just put "Yakety Sax" into YouTube's search bar and let hilarity ensue.