5 / 5


1. Celebrating tonight.
Odds are that Gomez's 21st won't be as wild and crazy as, say, Prince Harry's infamous romp in Vegas, but you never know. The brunette beauty does have a big night planned. As far back as April, she was talking about having a huge hip-hop-themed bash at her house to mark the occasion. Then, just last month, she shared a few more details. "My family from Texas, my friends [and] my cousins are flying in," the Dallas-area native told "Entertainment Tonight." "I will have some of my best friends in L.A." Just make sure to have guests drop off their cell phones at the door, Selena!

Selena Gomez's Bad-Girl Moments

Selena Gomez is a good girl, but the former Disney diva has had her bad-girl moments. In honor of her 21st birthday — a time when all of us have been known to cut loose — on July 22, take a look back at the rare instances when Selena showed her naughty side.