People who ask you a question to which you say "No", and then keep asking over and over and over.
"Bart works here, doesn't he?"
"No"
"You sure? Bart? Big guy, goatee?"
"No"
"Bart? You don't know him?"
"No"
"Yeah, Bart, he works here? Bald, big guy?"
"I ALREADY SAID NO, JESUS MURPHY! GET IT THROUGH YOUR HEAD"
"...So Bart's not here?"