Ooh, I always forget about the Far Side.
I quite enjoy Three Word Phrase. It's often short, quite silly, and often childish. This is why it's excellent.
http://www.threewordphrase.com/brofight.htm
http://www.threewordphrase.com/beedoc.htm
http://www.threewordphrase.com/mlady.htm
http://www.threewordphrase.com/gotme.htm
Personal favourites.