Britney Spears BSEARSHALOWEEN1031_26.jpgAfter leaving the house in her super-sexy catsuit, Britney Spears headed over to Heidi Klum's party at the Green Door with her two favorite X17 photogs. According to our source inside, she was escorted right to the best table in the house and started taking immediate advantage of its proximity to the dance floor - our source reports that Brit was "dancing and singing along to her favorite tunes which included Madonna and Michael Jackson"!

At around 1:15, the party decided to take off, but not before Britney could don another disguise - a rather conspicuous sombrero! Britney, however, was well aware of how goofy she looked - at one point, she even exclaims to the cameras "I look silly right now"! - although it certainly didn't keep her from wearing the sombrero the rest of the night, even as she rocked out to "Gimme More"!