2.An insult used towards a female/male when referring to her/him as a slut, to being highly sexually active and or guilty of participating in what is to be seen as unusual sex acts.
"So what you f***ed madd girls Tommy, that just makes you a nut job."
"ILL your room is a nut job!Don't you think its time to like CLEAN IT!!??"
The "Nut Job" has nothing to do with Sexuality. It is completely and utterly the term used to describe a Maniac, Just like a Nut Case.
In other words, it is an old man or stalker that has lost his mind; Or just a Hyperactive person that is all over the place and always looking for fun
(I don't always use the term do this example is going to be crappy)
DesertedChrome: "Yeah, I heard about him. He got arrested for multiple charges. He's a Nut Job"