Sidney and Thurman Sewell — the hard-partying identical twins who star in upcoming movie “Spring Breakers” with Vanessa Hudgens and Selena Gomez — lived up to their reputation at Vice magazine’s fashion issue party at GoldBar last week. Better known as the ATL Twins, the brothers were spotted partying in a small room with a DJ booth, where “one of them had a woman on his lap and then got up and took off his clothes so he was just in his boxers,” a spy said. “He was dancing around, and his butt was totally falling out of his shorts.” Maybe due to the debauched surroundings, our spy surmised, “It was strange only because it actually didn’t seem out of place.” Rapper Juelz Santana performed.