If you are in a mood for watching a really lowbrow, but funny movie, I really recommend that you go and see Year One starring Jack Black and Michael Cera.
I went today to see the movie and was constantly cracking up. Somehow this movie just hit me in the laugh nerve. I had to hold the laughs back a bit because I noticed that other movie goers did not sem to think that the humor was that fun. Maybe the others did not get all the jokes or then I am bit weird.
Eventhough the humor is really stupid the movie has a great positive vibe. There is also level in the movie that makes fun about religions and human nature. This probably gives the movie some depth and thus making Year One pretty darn fun and quite watcheable movie.