The whole incident went down at the Cash Money CEO's daughter's Sweet 16 b-day party in Miami over the weekend. A bunch of her dad's famous friends made her a personalized birthday message that played at the party, and Bieber's stood out the most.
Justin just celebrated his own b-day last weekend too. He reportedly partied with his friends and family in the Bahamas and brought on the big 2-0 like a good boy (with no arrests, that is). Watch him serenade the birthday girl in the video below.