UPDATE (September 8, 2011): apparently all of the videos below have been taken down due to copyright claims. What a shame. I guess you'll have to search for MythBusters bloopers yourselves.
So you enjoyed those Star Trek bloopers? How about a bunch of MythBloopers? BLOOP ON, FELLOW NERDS!
Warning: a brief NSFW moment when we fleetingly see, no kidding, Adam's derrière.
Drunkenness and Joking
Adam and Kari swap jokes. Becomes progressively more and more NSFW.
Slapping, Falling Down, and Face-Hitting
Includes many moments from the ongoing search for the elusive Hyneman. A few repeats from the first video above. I think most of these were aired, though if you like people getting (mildly) injured and calling out "I'm okay!" you'll love this.
Accidents Do Happen
"This is our show: it's, like, four minutes of science, then ten minutes of me hurting myself." -Adam Savage. This is the official, well-produced MythBusters-hurting-themselves video.