On March 2, 1996, at 1715 central standard time, a Cessna 150F, N8642S, registered to a private owner, and operated under Title 14 CFR Part 91, was standing with the engine operating, when a potential passenger outside the airplane contacted the propeller, at Jasper County Airport, Jasper, Texas. Visual meteorological conditions prevailed and no flight plan was filed. The rental airplane sustained minor damaged, and the private pilot-in- command and one passenger were not injured. The person who contacted the propeller sustained serious injuries. The personal flight was intended to embark the potential passenger, and fly in the local area. According to the pilot, she had just landed after a local sight- seeing flight with a passenger. As she was taxiing toward the terminal, a person, who was standing on the ramp adjacent to the taxiway, approached the airplane from the left (pilot's) side. She then stopped the airplane, idled the engine, and had a brief conversation with the person who approached the airplane. During the conversation, the pilot agreed to embark the person after her current passenger got out of the airplane, and go for a short flight in the local area. During the conversation, the person was located aft of the left wing strut. Several spectators, who were observing the activity from the ramp area, reported that, after the conversation with the pilot, the person turned to wave at them, and then walked into the propeller.