Our friends at SpyOnVegas.com were there as Jenna dressed up as a Pussycat Doll at PURE Nightclub in Caesars Palace last night to help celebrate her UFC fighter boyfriend's birthday. She popped out of a box and danced onstage -- and on Tito -- to Justin Timberlake's "SexyBack."

A couple of the Dolls then brought Tito a birthday cake. It probably wasn't the only piece Tito got that night.