You only turn 21 once, but Justin Bieber has celebrated the milestone three times now. Or maybe he was blowing off some steam after taping his Comedy Central Roast this weekend...
The 21-year-old continued to celebrate by jumping on stage and dancing at Omnia in Las Vegas over the weekend, and naturally, sang "Happy Birthday to Me" to the crowd.
However, his actual birthday was over two weeks ago on March 1, which he celebrated in an elaborate fashion by renting his own private island.
And never one to quit early, the Biebs also had a soiree in Miami with tons of bikini-clad babes last week.
Watch the video above to see Justin get crazy in the club!