Adele might be one of the most universally loved celebrities around, but that doesn't mean everyone likes her.

Case in point? Acid-tongued comedian Joan Rivers. The legendary comic has made a career out of calling it like she sees it, but has been recently criticized for being needlessly cruel towards the singer. She was booed on The Late Show with David Letterman while cracking jokes about Adele's weight, but that didn't stop her from flinging a second round of barbs during a recent interview.

"She wanted an apology, so I took an ad out on her ass. I said, 'You are not fat.' And then I had room for a lot of other ads," she said during a video chat on Huffpost Live. "She's beautiful and successful and has what, $100 million? Let's face reality: she's fat!"

Even before Letterman, she had gone out of the way to bash the singer who has yet to publicly respond to any of Joan's criticisms. "Congratulations to Adele on the birth of her 68 pound 8 ounces bouncing baby boy," she tweeted last October.

Related Article: Twitter Battle: Rihanna vs. Joan Rivers

Related Article: Is Adele The Most Expensive Celebrity Wedding Singer?

Of course, Adele was hardly the only person Joan took a swipe out during the interview. She said her time last year with Betty White as a guest star on her show Hot In Cleveland was one of the worst experiences of her entire career. "All of those girls were lovely and so were the crew, but the writers sucked," she said. "They gave me the script and it wasn't funny. I asked if I could help because, hello, I started out as a writer. But the word came down, 'Just tell her to do what's in the script.' It was horrible."

The Fashion Police host even managed to take exception to former Today co-host Ann Curry, who was unceremoniously given the boot last year. "Do you really like coffee? REALLY?! That's making me cry that you like coffee," Rivers cracked, impersonating Ann's heartfelt interviews. "I used to scream at the set, 'Shut up, b***h!'"

Although Joan's new internet chat show In Bed With Joan is one of the funniest things floating around the web at the moment, her cracks at Adele leave a lot to be desired. She's missing the irony of making fun of someone's appearance despite being so insecure with her own that she's just about mutilated her face with plastic surgery.

What do you think of Joan's fat jokes towards Adele?

Photos courtesy of Getty Images and CBS