#6 Three Amigos (1986)
This movie has got to be the greatest comedic trio performance of all time. Chevy Chase, Martin Short, and Steve Martin play three silent film actors go to Mexico thinking they are going to put on a lucrative live performance, only to come to a tearful realization that they're actually in Mexico, and that one of them has "been shot already!"
Just the costume design is enough to make me bust into tears laughing. How little these actors actually know is evident, since they are pretending to be cowboys, by dressing up as mariachi's. That, added with the singing bush, the invisible swordsman, the plethora rant between jefe and el guapo, and more, make for some of the most clever comedy ever to be filmed.