Sean Kingston performing at Nicky Hilton's birthday bash at Dusk

Nicky and Paris Hilton locked in a traditional sisterly embrace.

Nicky Hilton, Paris Hilton's sister, the one without a sex tape, for those keeping score, will celebrate her 26th birthday Saturday at Dusk inside Caesars in Atlantic City. Reggae/R&B star Sean Kingston will perform a few of his hits at 1 a.m. during the party. We hear that Lance Bass of 'N Sync and "Dancing with the Stars" will attend. A portion of proceeds from the evening will benefit MusiCares, a charity that assists those in the music industry who are in need.