A mildly offensive term that refers to a beirut or beer pong shot that misses back and to the left like John F. Kennedy's head did when he was shot (which supports the grassy knoll theory). Typically results from excessive follow-through from a right-handed shooter.
When Steve was starting his shot on the last cup, Tim shouted, "Your mom!" at precisely the right moment. This shocking insult hit too close to home and caused Steve to overdo his throwing motion, unleashing a wicked kennedy arm that sailed back and to the left of the cups.
by Nicholas D January 06, 2012