someone who sticks their dick between a womans boobs for sexual pleasure. chicks might be jugfuckers too, but that would be weird, and i dont know how it would work.
'To Juckle' refers to when you're doing math homework and you assume you know the answer to the question, so you don't bother doing it. By the you get to the end of your homework, you haven't actually written anything down. It is also an advanced form of procrastination.
"Hey Richard, how's that problem set going?"
"This shit's easy, I'm just jugfuckling."
"You better not jugfuckle the whole thing. We have a test tomorrow!"