floppy junk

Unwanted and excessive jiggling and swinging of the male genitalia during pelvic thrusting, often caused by the lack of restrictive underwear. Sometimes causes nausea or vomiting in others.

Girl #1: Did you see Johnny dancing last night? He had a seriously disgusting case of floppy junk going on.

Girl #2: Yeah, it made me want to blow donkey chunks. Jesus, buy some boxer briefs, dude.