Joan Rivers has never been known to hold her tongue when it comes to discussing pop culture, and the prologue of her latest book, “Diary of a Mad Diva,” is no exception. While Rivers' latest satire-laced novel takes shots at many of Hollywood’s leading stars, one in particular is reportedly threatening to sue the longtime comedian for her latest work.

“I’m now being sued by Kristen Stewart,” Rivers, 81, revealed to TMZ on Monday. The “Fashion Police" star added that Stewart, 24, is upset about the prologue's casting couch allegations. “She obviously didn’t read the disclaimer, which is that it’s a comedy book.” 

According to the gossip site, the prologue alludes to the former “Twilight” star's alleged affair with her “Snow White and the Huntsman” director, Rupert Sanders, now 43.

“Many stars only do one thing well," Rivers writes. "Of course, the best one-trick pony is Kristen Stewart, who got a whole career by being able to juggle directors' balls.” 

(For those unfamiliar with Stewart’s love life, the actress was accused of cheating on her longtime beau, Robert Pattinson, with the then-married director in 2012.)

Joan Rivers Joan Rivers answers a question at the E! panel for the television show "Fashion Police" during the Television Critics Association summer press tour in Pasadena, California, April 15, 2011. Photo: REUTERS

Rivers' response to the lawsuit threats? “My answer to her was be glad you’re not a Kardashian because they’re mentioned a lot more in the book,” Rivers told TMZ.

Despite the threat of a potential lawsuit, Rivers continued to bash the “Twilight” star on Monday, accusing the actress of having “zero” sense of humor and calling her a “fool” for taking the satire seriously.

"I can’t wait to get her to call, because I want to get a puppet and I want her to show me on the puppet where she thinks I claimed she touched her director,” Rivera said. “I’m looking forward to it.”

TMZ reported that Stewart’s lawyer originally reached out to Rivers’ “people” and threatened to sue for defamation unless the references regarding the actress were omitted from the book, which is due in stores July 1. While the controversial passage is said to have remained, sources close to the comedian claim they believe Stewart has since let the matter drop. “It’s been radio silence since the threat was delivered,” the report said.

Rivers’ book also caused controversy with its comments about “Girls” star Lena Dunham’s weight. According to reports, Rivers addresses the TV star’s appearance by referring to her as the “first fat girl naked on television.”