To masturbate in class. Possibly done by shaking your legs so your thighs hit your wang.
Dude #1: Did you see Dave?
Dude #2: No, what'd he do?
Dude #1: He was baumgarting it.
Dude #2: That noise was his leg hitting the table! That's messed up...
by Big_D_and_the Revolution December 11, 2006
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