Fergie wore a destroyed T-shirt Friday and we could see her skin right through the holes ... not to mention her belly button!

The toned and taught Black Eyed Peas singer wore the tease-y t-shirt on her way to Vegas for the Billboard Music Awards. She didn't waste time once she hit Sin City, the wild child was out partying at Haze Nightclub at the Aria Hotel and Casino last night.

And while Fergie danced the night away, her hubby Josh Duhamel was back in LA taping The Ellen DeGeneres Show and wearing an even sexier outfit than his wife's ... click through to see Josh in tights!!!