"Tommy Boy" the whole movie, but especially when the buck wakes up in the back seat of the car.
"American Pie" - one of the all-time classic lines: "and this one time, at band camp, I stuck a flute up my pussy."
"Planes, Trains and Automobiles" - in the rental car with John Candy driving while Steve Martin is asleep and he gets both sleeves caught while trying to take off his coat.
"Naked Gun": the hospital scene with Nordberg in a body cast in the bed.
"A Christmas Story" when the dogs break in and tear apart the turkey.
"Airplane" the entire movie.
"Boomerang" when Grace Jones is trying to seduce Eddie Murphy in the restaurant by throwing her leg up on the table and yelling "Look at this pussy. No man can refuse this pussy."
"Caddyshack" when Rodney Dangerfield shows up at the country club.
 I forgot one that I had to mention. The scene in "Caveman" where they invent music.