Like a knee slapper, but when you're mad the joke isn't funny.
Burt: Why did the chicken cross the road?
Haley: IDK WhY?
Burt: To get to the other side.
Haley: (Screams and slaps leg really hard) That's a leg slapper!
by MultiAwesomeGirl123 April 24, 2010
Get the Leg slapper mug.