Chill with his grandparents, of course.
"Hopefully my grandparents will be out here and I'll be able to spend time, a little bit, with them," the singer tells Entertainment Tonight in an interview airing Thursday. "My grandma makes the best cheesecake – cherry cheesecake. She made that for my 13th birthday."
Bieber insists there will be "no birthday bash," especially because of the short window of time he has before he gets back to work.
"I only have, like, four days, so I'm just going to relax, because I start my world tour starting on [March 4] – so just going to mentally prepare and just relax," says Bieber, whose birthday is March 1.
The star also warns fans not to read too much into his recent haircut.
"I just woke up and said, 'I don't want this anymore,' so I just cut it," he explained of the decision to shear his famous locks. "You know, the fans really liked it, but they'll like me no matter what, because I think it's about the music."
Please note: Comments have been suspended temporarily as we explore better ways to serve you. Your opinion is important to us; you can find current discussions at facebook.com/peoplemag.