A knuckle punch is when two fists collide in a totally ungay way. Its a proper word for what some GAYS call 'fist bump'.
Cause obviously bumping fists makes no sense.
KNUCKLE PUNCH ALL THE WAY.
Sarah - OH EM JEE DO YOU WANT TO BUMP FISTS?
Me- No. But I'm willing to do a knuckle punch with that sexy boy toy of yours.