A blonde walks into her first college exam of the year and sits down. Everything is going well except that every couple of minutes the blonde looks up from her test, stares straight ahead, and claps twice. The professor says nothing for awhile but after about thirty minutes of this, he can't take it any longer and asks the blonde why she insists on clapping twice every few minutes. The blonde looks at him as though he is the biggest idiot in the world and in a very saucy manner answers him saying...
"The light bulb that goes on above my head when I get an idea is hooked up to a clapper. DUH!"