More stupid names for terrifying occurances.

In medical parlance, a charley horse is a painful contusion of the quadriceps muscle of the anterior thigh that commonly results in a muscular hematoma and sometimes several weeks of pain and disability.1,2 It often occurs in sports when an athlete is struck by an opponent's knee, in a manner not unlike the kick of a horse, perhaps the reason for its name. In the UK, such an injury is known as a corky, or corkie.

In recent decades the term has also been used to describe painful leg cramps, which may occur in the thigh, arch of the foot, calf muscle, or quadriceps.
-http://en.wikipedia.org/wiki/Charlie_horse