S6, E4: After Bonnie (Jennifer Tilly) tells Joe (Patrick Warburton) that she is tired of being married to a handicapped person, Joe decides to get a leg transplant. Excited about his new ability to walk, Joe dives head first into extreme sports and begins to hang around more active friends. Meanwhile, Peter and the guys are upset at how Joe is acting and decide to teach him a lesson. In doing so, they re cripple him and he is back to normal.