The act of dunking on an opponent in basketball where your crotch goes directly into their face as you jump over them for the slam. The humiliation can be further amplified by hanging on the rim to keep your sweaty junk pressed into their face.
“Lattrell didn’t just posterize that boy, he Junk Dunked on him.”
“Hey man, did you get a good look when he Junk Dunked on you? Was it boxers or briefs?"