Audrina Patridge posed in her bikini at the MGM Grand pool in Las Vegas yesterday. She was in town to celebrate her 26th birthday, which was actually May 9, with friends and family and enjoyed a tiered cake and a day in the sun to kick off her weekend bash. Audrina's brother, Mark, was on hand for the fun as was her on-again guy Corey Bohan, who is back in the picture after their breakup in March. Corey took advantage of the trip by meeting up with pals for lunch before joining the birthday girl to continue the festivities into the night with a dance party. Audrina has plenty to be excited for as she rings in another year, including her VH1 reality show, which is currently airing, and a new web series for Yobi TV.