Similar to the term "poser". A nob head is a person trying to gain attention by bringing themselves down socialy. This kind of action may annoy most people rather than entertain. Nob heads only distribute entertainment when a large ammount of alcohol is consumed.
"look at patric over ther trying to pull his undies out of his pants. what a knob/nob head!"
"Hey, thats mine! Dont be such a knob/nob head!"