Here are my favorites by genre:
Comedy:
Any movie by the Zucker Bros. (Airplane, Naked Gun trilogy, High School High) and/or featuring Leslie Nielson.
Smokey & the Bandit (1&2, 3 is kinda wack).
Police Academy 1-4 (5-7 are weak w/o Steve Guttenberg).
Any Jim Carrey flick (They're stupid, but you just can't help laughing).
The Out of Towners (the original 1970 flick with Jack Lemmon is TEN TIMES better than the current Goldie Hawn/Steve Martin remake).
The Odd Couple II (that argument b/t Felix and Oscar about the trifecta/fourfecta/fivefecta had me ROTFLMNBAO).
Animal House
Drama:
Patton (a MUST RENT)
Nixon (I have never heard a president cuss so much in my life)
JFK (got a little longwinded after a while, but still good).
The Negotiator
Pulp Fiction ("This is a TASTY burger!")
Titanic
Brittanic (sister ship to the Titanic and having a similar plotline to that of Titanic)
Horror
April Fools Day
Disaster
Any of the "Airport" movies ('70,'75,'77,'79)
The Poseidon Adventure
Earthquake (1974)
Earthquake in New York (1999)
The Los Angeles Earthquake (1990)
Hurricane
Volcano
The Day After
Sci-Fi
Any movie parodied by Mystery Science Theater 3000
MST3K: The Movie
Black (predominately Black cast)
The Josephine Baker story
Introducing Dorothy Dandridge
House Party trilogy
Booty Call (a little on the ghetto side, but HEE-LARIOUS).
Nutty Professor
Jo Jo Dancer
Soul Food
The Court Martial of Jackie Robinson
Adult:
Email me for this one (just kidding, just kidding

)
Sorry so long.
Rain Man