look up any word, like plopping:

1 definition by IXI BLITZ IXI

 
1.
HBM
Head bob movement. The bobbing of ones head when they approve of something, usually with a smile. Most often used over an instant messenger service.
Guy: Dude, I just got a new car!
Guy 2: HBM, thats sweet.
by IXI BLITZ IXI October 21, 2010