Freeballin. When a guy goes without underwear in shorts that show his vpl( visible penis line) or his dick is visibly flopping around. It's especially common among jocks at the gym, or when playing basketball or volleyball.
Poof: Damn, all those boys are free swingin!
See freeballing, commando, going commando, free balling, free ballin, free and breezy, package, bulge, moose knuckles, bean bag, bean bags, wranglers, melvin, vpl, visible penis line, Jackson 5