here's your sign

A sarcastic remark and gesture that is said and done when someone says something stupid. This is said while holding the back of your right hand in a fist to your forehead with the index finger and thumb extended to form an "L" for "Loser." This is done and said to someone when they ask an obvious question and they should have known the answer; it points out to someone how dumb the question was that they just asked.