It seems as though Joan Rivers is always upsetting a celebrity.

In her new book, "Diary of a Mad Diva," she talks about Kristen Stewart in a less than flattering way.

"Many stars only do one thing well," she said in her book. "Of course, the best one-trick pony is Kristen Stewart."

She goes on to explain that Stewart has used sex to propel her career.

"I'm not being sued by Kristen Stewart," Joan Rivers told TMZ. "She obviously didn't read our disclaimer, which it's a comedy book. And I can't wait to get her to court because I want to get a puppet. I want her to show me on the puppet where she thinks I claimed she touched her director."

Rivers said that Stewart's lawyer has contacted her lawyer.

She added that she thinks Stewart is being too sensitive.

"Yeah, which shows the sense of humor she has," Rivers said. "My answer to her is: Be glad you're not a Kardashian 'cause they're mentioned a lot more in the book."

Stewart's lawyer threatened to sue for defamation unless Joan Rivers got rid of the reference, which is presented as fact, though the prologue says it is satire. Of course, Stewart made headlines for having an affair with married director Rupert Sanders, so it might lead people to believe that what Rivers wrote is true.

Rivers has said that the tidbit on Stewart will not be removed in the book that is to be released early next month. Since the initial contact, Stewart's lawyer has not continued to contact Rivers.

Rivers said she doesn't understand why people are still offended by the comments she makes.

"I'm a comedian," she said. "I've been doing it for 50 years. If people don't get it, don't come see me. It's OK. Don't read the book. If you're going to take it seriously, you're a fool."