One who gets around and/or carries many std's and sti's. Avoid these individuals at all cost because of their ability to easily transmit venereal disease. Synonymous with petri dish.
Mike: Wash your hands after talking to that girl.
Mike: She is a complete nettleton. You could honestly contract anything from her.
-2 weeks later-
Johnny: Dude why does it burn when I pee now?
Mike: You should have washed your hands...
Someone who is very annoying but everyone loves, thinks is awesome, and can't help but to hang out with, yet no one will go out of his/her way to hang out with.
C: You're annoying.
J: But people love me.
T: I know I do.
J: And I'm awesome.
T: No doubt!
J: T... why have you never invited me to anything or texted me before I texted you?
C: 'Cause you're a nettleton.