RiRi held a star-studded birthday bash after the NBA All-Star game in LA on Sunday night. Perhaps THIS was the main reason she cancelled, Mr. Trump. The guest list was a who’s who of the entertainment business, with everyone from Jay-Z to Zac Efron in attendance! “She [gave] Ryan Phillippe and Zac Efron huge hugs,” an insider from the party told People mag. ‘Cee Lo Green and his crew were spotted too, noshing on some oxtail and plantains. Mary J. Blige and Jay-Z, who were “laughing and having a blast,” posed for photos in a corner, the source adds. Blige also “squealed with excitement” when she caught sight of Diddy, and then hugged him. “Snoop Dog and Warren G rolled in at 1 a.m. and proceeded to dance and sing along to some old-school hip-hop songs while guests cheered them on. Joel Madden and Christina Milian were also celebrating with the birthday gal, and indulged in vanilla and red velvet cupcakes.” Sounds like it was super fun! Hit the jump for some flicks from the evening. @MarisaMendez