Parts that were actually funny.
I'm with a lot of people in thinking this film was...ok, but sadly did not live up to the first one. (which is probably pretty hard to do, but still, I was expecting better.) However, I did crack up at a handful of scenes:
Harry's fantasy of being a father, smacking Penny in the face with a door to knock her tooth out. And later on when Lloyd shows up, dirty and waddling down the street in skis and a tutu to eat the garbage.
Scaring Billy in 4-C.
Harry going deaf.
Lloyd laughing at Harry's Asian parent's language.
The flashback of them laughing, while flipping their car as teens.
Walking through the entire row of people at the uni-lecture to get to their end seats.
The Mutt's Cuts van cameo...didn't make me laugh so much as it made me emotional. As soon as I heard that guitar riff, I felt a wave of nostalgia.
I'm sure there are more that I'm missing, as it's been a while since I've watched the movie.