Such a stunner! Too bad she didn't run into the Biebs, because we have a feeling he would have been speechless -- either that, or she would have ended up back at his place!

Selena Gomez stopped by The Nice Guy in Hollywood on Friday night, and the 22-year-old singer/actress showed some skin in a sexy black and white cut-out dress. Of course, even if ex Justin Bieber was wowed by this outfit, it sounds like the two are back on rocky terms. What's going on this time with Jelena? Apparently it's all about his new song, "What Do You Mean."

An insider tells Celebrity Dirty Laundry, “Selena was really hoping that Justin would mention her [in the new track], or at least make it obvious the song was about her. That song could have been about any girl. She was banking on his song creating a ton of buzz to help her promote her new album.”

The insider added, “Justin was always insecure about his relationship with Selena, because he constantly felt like she was using him to further her career. Now, the stunts that Selena is pulling are only cementing Justin’s old fears. He tried to win her back this year, and she basically stomped on his heart and then turned their hang out session into a photo-op. He feels like he was right all along about her using him, and their three year relationship was all a publicity gimmick to her.”

Wow! And not only that, but when Justin sat down with Ryan Seacrest on Friday, it seems like he called out his ex for bitchy behavior. “Do you look at text messages before you go out [on stage],” Ryan asked. "Because that could throw you off.” Justin shook his head and replied, “It can. It can. I’ve had an ex-girlfriend scream at me before going onstage and stuff.”

Was he talking about Selena?!