William Goldman, genius Oscar-winning scriptwriter of All The President's Men, said There's Something About Mary should have won the Best Picture Oscar of that year - he makes the point that straight comedies never win, even though they are the hardest movies to pull off (if you will). He deconstructed the opening zipper scene as one of the funniest ever. The hair gel scene is very funny too, mainly from the conversation beforehand - "it would be like going out with a loaded gun!"
Rarely has such sweetness and crudity existed alongside each other. Mary is far and away the Farrely's finest hour, and is a worthy contender for best comedy alongside the Pythons.
When Harry Met Sally is another film that is still laugh out loud funny in many places...