kicks off his birthday celebrations early as he heads out with ex-girlfriend Karrueche Tran. The R&B star — who is 24 on May 5 — started his partying at the Emerson Club in Hollywood while his current girlfriend Rihanna was far away on tour. He appeared to have forgotten all about the £700,000 Mercedes-Benz birthday present the 25-year-old singer bought him for his special day as he partied with his former flame. Christina Milian, Chloe Green and Corey Feldman also joined the Don't Judge Me singer. The blonde-haired star wore a casual chequered shirt over a crisp white T-shirt with khaki chinos. And Karrueche also dressed down with a studded denim jacket over an LBD teamed with peep-toe white tassle boots TheSun