Paris Hilton was revealed to be lip-syncing to her hit song 'Stars Are Blind' at her birthday party on Saturday (07.03.09) when new boyfriend Doug Reinhardt took the microphone off her, only for the song to continue playing.

Paris Hilton was left humiliated at her birthday party after her new man exposed her lip-synching.

The socialite - who flew by private jet to Las Vegas with 15 friends to belatedly celebrate turning 28 - was horrified when lover Doug Reinhardt grabbed her microphone as she was performing her song 'Stars Are Blind' at the Body English night club at the Hard Rock Hotel and Casino on Saturday.

Before her rendition, Paris paid tribute to Doug, gushing: "My man is right over there, the sexiest man in the world."

During the evening, Paris - whose birthday was on February 18 - was entertained by Chester French and then presented with a giant pink mushroom-shaped cake decorated with a butterfly before heading up to the Penthouse suite at 3am to continue partying.

They were greeted by the Sesame Street band, playing in a room filled with balloons and circus performers.

Paris had already celebrated her special day in New York, Los Angeles and Tokyo.