Mad Men star Elisabeth Moss shared some negative feelings about Jeremy Piven on Bravo's Watch What Happens Live.

Moss was a guest on the show Thursday night and opened up about PIven, who co-starred with her on the 2008 Broadway revival of Speed-the-Plow. Piven famously left the production early on after getting mercury poisoning.

Moss's comment came after host Andy Cohen asked, "What besides eating too much sushi caused Jeremy Piven to leave Speed-the-Plow?

"That's a good one, that's a very good one," she responded, "I could go on and on . . . Being highly unprofessional."

Moss added, "He just didn't come back one day . . . I saw him, like, a month later at The Golden Globes when he was supposed to be really sick."

Piven received criticism that he was just using the mercury poisoning excuse to get out of working.  A source from the Speed-the-Plow production team told Gawker in December 2008 that they doubted Piven's claims.

"Jeremy showed NO exhaustion as recently as last week," the insider said. "For six weeks, he has been trying to weasel out of his contract, citing various forms of exhaustion (nothing about mercury until a few days ago), while still going out and partying constantly into the wee hours."

Piven responded to the criticism in a March interview with The New York Times.

"I think once a stage actor, always a stage actor. I'm from a theater family. I am what I am. You really can't control the rest of it. You can try. You can rail against the universe for being misunderstood. But I don't know how healthy that is," he said.

The rest of the interview with Moss comprised of talking about Mad Men but more specifically about co-star Jon Hamm's penis. Hamm received media attention when word got out that he was asked to wear appropriate clothing to cover his large bulge.

When Cohen asked Moss if the rumors were true about "Jon Hamm's ham", the actress replied, "Well I mean we have all seen the picture, so I suppose so. That is all I know."

Moss has starred as Peggy Olson on Mad Men for six seasons, receiving an Emmy nomination for her work in each of the last four years. This year, she also starred in the Sundance Channel miniseries Top of the Lake.

See the diss and much more here:

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