Joel Heyman plays Michael J Caboose, the rookie on the blue team. He's the funniest character and is #1 in my opinion. Heres a quote from one of their PSAs, Planning To Fail:
(pretending to be zombies)
Caboose: Brian! I want Brian!
Tucker: It's brains, Caboose!
Caboose: Oh, I must've been reading the script wrong. Moaning, moaning!
Joel is the best! :)