Cameron's Lap Dance for Justin

05/26/2006 at 06:00 AM EDT

Cameron Diaz showed Justin Timberlake that he's not the only one who can rock his body when she treated him to a playful lap dance during a recent night out in Las Vegas. The couple, in the house at the Bellagio's Light nightclub for manager Rick Yorn's birthday party, were thisclose all night, cuddling and kissing. Along with pal Trace Ayala and a group of about 15 friends, the pair drank Dom Perignon and Grey Goose and held court in a corner VIP area near the deejay booth. At one point, they even encouraged each other to dance on top of the Light banquette. And they partied until the bitter end, staying until the club's lights came up.

Baby Got Back

Most women wouldn't relish adding extra pounds to their booty, but Penelope Cruz was excited to try out the prosthetic bum she wears for her role in Pedro Almodovar's dramedy Volver. "It was great when we found it!" the petite actress told us at the Cannes Film Festival. "All the energy went down there and usually, because of my years of ballet training, it is up (by my shoulders). So it was strange for me at first." No word on what beau Matthew McConaughey thought of her enhanced posterior.

Caught in the Act

• Heather Locklear, hanging out with David Spade at a dinner party at L.A. eatery Republic. When the comedian arrived an hour after Locklear, she greeted him with a hug before bringing him to the table to join the rest of the group.

• Stevie Wonder, serenading Janet Jackson with his song "Happy Birthday to Ya" at her 40th birthday party at Hollywood club Shag. The guest of honor, who was dressed in white, "looked like she was a teenager – amazing," says a source. On hand for the intimate bash, which featured huge arrangements of pink-and-white roses and a small cake: Paris Hilton, Travis Barker and Joe Simpson.

• By MONIQUE JESSEN, AMY ELISA KEITH and MARISA LAUDADIO