Kelly Osbourne Slams Christina Aguilera, Calls The Singer A 'Fat Bitch'

Kelly Osbourne has never been Christina Aguilera's biggest fan. Anyone remember Kelly's infamous impersonation of Christina during an episode of "The Osbournes"? But just when we thought these two had stop feuding, a slimmed-down Osbourne decided to take their cat-fight to a whole new level--during an episode of E!'s Fashion Police.

Joan Rivers thought that Aguilera looked a little too "stuffed into" a black Givenchy dress, and the comedian even likened the singer to "Snooki's Scandinavian cousin" (ouch!). But Osbourne took the criticism one step further and replied: "Maybe she is just becoming the fat bitch she was born to be. I don't know. She was a c**t to me. And she bought my house!"

Osbourne's digs at Aguilera's weight gain continued. "She called me fat for so many f***ing years," Osbourne said, "so you know what? F**k you! You're fat too."

Osbourne knows what it's like to be called fat. In an interview with Us Weekly, she opened up about her weight struggles. "I took more hell for being fat than I did for being an absolute raging drug addict," she told the magazine. Osbourne was checked into rehab for drug and alcohol addiction three times. "I will never understand that."

The 5-foot-2 Osbourne once weighed "almost 160" pounds, but she shed more than 48 pounds because of her 2009 stint on "Dancing With the Stars", and she's managed to keep it off.