when a male thrusts forward so quickly, his dick and balls slap against his stomache, causing a "clapping" sound
Sarah: At Lisa's party we dared Steven to happy clap for a beer and he did it..twice!
by chandramukhi January 22, 2008
(for males) when the balls slap together with the thighs of your leg.
may happen when u shake your leg
by Philip March 24, 2005