A sudden "jumping" or rising motion of an erect or half-erect penis. This motion is actually caused by flexing muscles of the pelvic floor and muscles at the base of the penis.

A character may consciously cause this motion by flexing those muscles or it may be caused involuntarily with contractions that occur during orgasm. This motion can often be seen as a character is becoming erect.

This motion is frequently seen along with the penis throbbing.