Justin Timberlake, Mila Kunis
Credit: SPE Inc./Matt Dames via Getty Images

Justin Timberlake and Mila Kunis (in Monique Lhuillier) headed south of the border to promote their romcom Friends With Benefits in Cancun. "When we were doing rehearsals we realized we don't hate each other, which was a plus," Kunis told Access Hollywood, when asked about the pair's amazing onscreen chemistry. Click through the gallery to see Naomi Campbell, Kate Moss and more stars at last night's hottest parties!