UPDATE: Here are the latest rankings as of BamaThrasher's post on Apr 6, 2011 2:07 PM CDT:
1) Holy Grail
3T) 40 Year Old Virgin, Anchorman, Animal House and Office Space
4T) Dumb & Dumber, The Big Lebowski, The Hangover and Tommy Boy
I am inlcuding comedy/live shows like Eddie Murphy Raw so feel free to include those if you like. Basically if the movie made you laugh so loud and frequently that you were crying tears of joy OR you almost had/did have bladder issues, it qualifies.
1) Monty Python and the Holy Grail - whether it's your favorite color, the wing velocity of a bird or a good duel with the Black Knight - this one is tops in my book. Also, you need to watch this movie several tims as actors in the background are doing some funny stuff as well.
2) 40 Year Old Virgin - This one had me in tears throughout the movie.
3) Dumb and Dumber - Maybe this is more of a guy humor type of thing as I have found people to either love or hate this one. For me it was VERY funny - "A million to 1 - SO THERE'S A CHANCE!!"
4) Eddie Murphy: Raw - Charlie Sheen could have taken some notes from Eddie as I'm sure Detroit would have appreciated better preparation and content.
5) Bill Cosby: Himself - A true comedy artist - HIGHLY recommend - Very clean and still very funny.
6) Airplane - Classic
7) Planes, Trains and Automobiles - "Those aren't pillows!!"
8) Vacation and Christmas Vacation
10) Animal House