Update: Rep Defends Miley Cyrus' 'Stoner' Comments As 'Sarcastic'

Miley Cyrus arrives at The 53rd Annual Grammy Awards held at Staples Center on February 13, 2011 in Los Angeles, California -- Getty Images

Kelly Osbourne has leapt to the defense of friend Miley Cyrus after a video emerged on Sunday showing the teen actress/singer joking about marijuana at her 19th birthday party last week.

In the video (obtained by The Daily), Miley can be seen laughing with friends before thanking revelers for a cake featuring the face of reggae icon Bob Marley, saying, "You know you're a stoner when your friends make you a Bob Marley cake -- you know you smoke way too much f***in' weed."

PLAY IT NOW: Access Hollywood Live: Kelly Osbourne On Her Brother Jack’s Engagement - ‘He’s All Grown Up’

However, Kelly, who threw the birthday bash for the former "Hannah Montana" star, says the cake and subsequent comments were simply making light of Miley's highly-publicized salvia incident in 2010.

"Let me make something very clear after Miley Cyrus' salvia incident we started calling her bob miley as a JOKE!" Kelly Tweeted on Sunday. "The cake was also A JOKE! It makes me sick that Miley Cyrus' so called 'friends' would sell her out and lead people 2 believe she is someone that she is not!

VIEW THE PHOTOS: Hollywood’s Famous Friends

"U guys if Miley Cyrus is not recording/filming/touring she is works everyday how could she possible do all that if she was a stoner! #think," she added.

A rep for Miley was not immediately available for comment on the video when contacted by Access Hollywood on Sunday.

Copyright 2011 by NBC Universal, Inc. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

VIEW THE PHOTOS: The ‘Fierce’ Miss Kelly Osbourne