The Insider.com

Celebrity rule number one -- Don't say things on Twitter you might regret later.

• March 13, 2012Beyonce's Dad Opens Up About Blue Ivy
• March 13, 2012Rewind: Natalie Portman Shaves Her Head
• March 12, 2012Upgrade / Downgrade?
• March 12, 2012Kim K Fires Back at Jon Hamm
• March 12, 20125 Things You Don't Know About Jennifer Lawrence
• March 12, 2012Surprising Hookups

Adam Levine is learning this the hard way, when his fellow The Voice judge Christina Aguilera took it upon herself to call out his hypocrisy concerning his first foray into the celebrity fragrance game with his upcoming men's and women's fragrances "222."

Christina Tweeted a link back to a March 2011 Tweet of Adam's, which read, "I also would like to put an official ban on celebrity fragrances. Punishable by death from this point forward."

"Haha @AdamLevine," Aguilera wrote in reply. "What a difference a year makes …"

Eeeek.

Adam Levine's Twitter War With Fox News Anchors

She did however, wish him the best of luck with his new venture, writing, "Welcome to the celebrity fragrance family!"

Though her comments seemed to be all in good fun, it seems like she really dug deep to embarrass Adam, no? After all -- there's few things more embarrassing for a band's reputation than being accused of selling out, and let's face it -- he so obviously has.

Adam Levine: Shame on Randy Jackson

Seems to me like there really is a legitimate beef behind these two's on-screen tension!