Among firearm circles, particularly when talking about self/home defense, the issue of overpenetration is frequently mentioned. Well, read about an experiment by the MythBusters gang gone horribly awry while they were firing a cannonball. I have to admit, it's almost comical to read about what and how far this cannonball traveled. I kind of imagine some cartoon character with this bowling ball-sized hole through his torso. But obviously, it's a dead serious thing. Any number of unlucky people could've been killed.

I sure hope this isn't the end of MythBusters experiments based on projectiles.

You can read about it here.