In no particular order:

Animal House
Annie Hall
This Is Spinal Tap
Tucker & Dale Vs Evil
Napoleon Dynamite

I laughed my ass off at Tucker & Dale vs. Evil. Brilliant, hilarious movie.

I hope you found your ass after laughing it off or that would be a sad state of affairs.

The dude that played Dale was hilarious in the show Reaper. I think that's where I first saw him.