When one pretends that his or her legs don't work. This syndrome often comes on without any warning, causing the person to lose control of their legs and collapse immediately. The legs then become dead weight which must be dragged around until they regain life.
This was first documented in the TV series LOST, in which John Locke lost feeling in his legs and would suddenly collapse while walking.
Kyle: OMG, did you see Sarah collapse when she tried to stand up?
Katie: Yeah, at first I thought she was paralyzed but then I realized she was probably just John Lockin' it.