RedactedNarrative: Vessel #1 travelling in a southerly direction at approx. 25-30 mph.  Passenger #2 moves quickly to front of the boat and kneels on bench seat on starboard side and pulls down shorts as if to pee.  Operator backs off Throttle and Passenger #2 falls overboard and goes underneath vessel.  Passenger #2  struck by lower unit and sustained a fractured pelvis and open tibia/fibula fracture and laceration to lower right leg.