A combination of bare assed and buck naked. Another form is buck ass
nekkid. Usually applies to a drunk
frat boy types in
innocent homo-erotic situations while hard drinking with their buddies.
Josh: "Hey, that
Chad guy is buck ass naked and sportin' a
semi."
Jake: "Yep, he's a nudie."
Jeremy: (as he drops his boxers) "Yeah, he'll nude up any
time, anywhere."