If Miley Cyrus is trying to separate herself from her past as a Disney TV star, she's doing an excellent job: Celebrity BFF Kelly Osbourne has had to come to Cyrus' defense yet again after the singer joked about being a stoner at her 19th birthday party.

You know you're a stoner when your friends make you a Bob Marley cake, Cyrus said in a video leaked to The Daily. You know you smoke way too much f*ckign weed!

In the hours since the video went viral, Kelly Osbourne, Cyrus' friend and the host of her now-infamous birthday bash, took to Twitter to defend the Can't Be Tamed singer from those slamming her statements in the video.

If Miley isn't recording/filming/touring, she works every day, Osbourne tweeted in a series of Twitter post after The Daily posted the video. How could she possibly do all that if she was a stoner?

Osbourne, 27, also defended an exchange where she and Cyrus joked about the singer allegedly smoking marijuana last year. At the time, Cyrus claimed the bong she was caught smoking contained salvia, a legal hallucinogen. Osbourne says the incident had become a long-running joke for the pair.

Let me make something very clear: After Miley's salvia incident we started calling her 'Bob Miley'! Osbourne tweeted. The cake was also a joke.

She also lashed out against the anonymous source that called Cyrus a pothead and leaked the video to The Daily. It makes me sick that Miley's so-called 'friends' would sell her out and lead people to believe she is someone that she is not! she said.

Miley Cyrus' brushes with bongs aren't the only times the singer has been slammed for a controversial career move. The former Disney Channel star seems to be doing everything in her power over the last few years to divorce herself from her good-girl image, including a pole dance in 2009 and a barely legal photoshoot in 2008.

Whether or not Miley Cyrus actually smokes weed, the singer has certainly come a long way from her days as the star of TV show Hannah Montana. The star now has nine tattoos, is best friends with the daughter of Ozzy Osbourne, and is currently joining British songstress Adele to record a Bob Dylan tribute album, covering You're Gonna Make Me Lonesome When You Go.

Take a look back at Miley Cyrus' biggest career controversies, as she transformed from Disney Channel princess to racy teen singer.