Lisa Kudrow was told she was ''f***able'' by an unnamed 'Friends' guest star after going through hair and make-up.

The 53-year-old actress - who portrayed Phoebe Buffay in the popular sit-com - admitted the unnamed actor exhibited the ''worst behaviour'' she'd ever seen during her 10-year stint on the show.

Asked the worst behaviour by a guest star, she told 'Watch What Happens Live' host Andy Cohen: ''The worst behaviour just off the top of my head? I rehearsed without make-up most of the week and then on show night I'm in hair and make-up and I was told, 'Oh wow, now you're'--can I say it? 'Now you're f** kable.

''That's bad behaviour, I say.''

But Lisa admitted she had little to say in response.

Asked if she had retaliated, she laughed and said: ''I told Matt LeBlanc. He's like a big brother.''

Despite being grilled as to who the mystery actor was, Lisa refused to say, though she did confirm it wasn't Charlie Sheen.

Lisa previously admitted that while she likes to see the rest of the cast - which also included David Schwimmer, Jennifer Aniston, Courteney Cox, and Matthew Perry - socially, she isn't interested in an on-screen reunion.

She said: ''Me personally? No. But we have convened, privately, for dinner and it was great.

''It was really fun. We had a good time. It was hilarious and we were laughing non-stop. That was really mean. But if we don't tell you one is coming and then it doesn't happen, you have no reason to be disappointed. I'm managing expectations.

''I don't see it happening. It would be fun, but what would it be about? Think about it. The thing we liked best about the show was that they were 20-somethings and they were their own family. Now, they all have families, so what are we going to watch?''