The horrible thing that a celebrity guest star said to Lisa Kudrow while filming Friends

The popularity of Friends resulted in a slew of well-known actors and actresses wanting to guest star on the show. 

Brad Pitt, Reese Witherspoon, George Clooney, Robin Williams and Julia Roberts were just some of the big names that starred on the hit comedy. 

Now, Lisa Kudrow has revealed that not all of these celebrities were as nice and friendly as they should have been. 

Lisa, who played Phoebe, was asked on Watch What Happens Live With Andy Cohen to tell the worst behaviour by a guest star on the series, and she delivered.

"The worst behaviour just off the top of my head? I rehearsed without makeup most of the week and then on show night I'm in hair and makeup and I was told, ‘Oh wow, now you're'—can I say it? ‘Now you're f--kable," Kudrow told Andy Cohen. "That's bad behaviour, I say."

"Did you retaliate?" she was asked.

"I told Matt LeBlanc," Kudrow laughed. "He's like a big brother."

Cohen grilled Kudrow on the guest star's identity, but she wasn't naming names. She did however confirm it was not Charlie Sheen.

To IMDB we go, Friends fans!