for my friends, it's Christopher Guest movies (mostly Waiting for Guffman), The Princess Bride (which ironically has Christopher Guest in it), Monty Python movies, Boondock Saints, and Anchorman. It's ok, because I actually liked all but Anchorman a lot. Anchorman just bothers me, other than the fight scene.
quoting Borat is worse than quoting Napoleon Dynamite. srsly.
oh, and it's not a movie, but people quote The End of the World video all the time. and this one guy i know says, "OMG SHOES" all the time from that Shoes video.