And there was the joke that started it all, a decades-old bit by Liebman about dating: "I'm pretty old fashioned. I like it when the guy pays ... for sex." And Schumer, from her stand-up last year: "I am very old school. I think the guy should always pay on the first date ... for sex."
Schumer moved fast on Twitter to deny the accusations. She then appeared on Sirius XM's Jim Norton Advice Show, where she emphatically reiterated that she had never stolen another comic's jokes: "I would never, ever do that, and I never have." She added that she was "literally going to take a polygraph test" to prove her innocence.
Schumer expressed admiration for Madigan, Liebman and O'Neal, and insisted that she had never seen any of the original material she was accused of stealing: "I have to come up with so much material - the TV show, this movie, stand-up, and I'm so careful. And none of these things had ever reached me."
She said she was on good terms with Madigan and Liebman, and suspected that Pescatelli was the one with a problem: "Both Kathleen and Wendy believe me, they know me, and they don't believe that I would do that," she said. "I think this is Tammy trying to get something going."
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Schumer and Norton both noted that it wouldn't be a wise move to steal the work of comedians she has publicly praised. "I just would never do that," she said. "That would be so stupid for me to do that."
On Wednesday, Liebman tweeted a clarification of the comment that started the fracas:
"I never said @amyschumer stole my joke. I just said it was the same. It's possible we both wrote it. I just wanted you to know I wrote it 1st."
And other comedians, including Aziz Anzari, Colin Quinn and Norton, came to Schumer's defence.
Pescatelli, meanwhile, stuck to her guns and seemed bemused at the suggestion that she had engineered the attack against Schumer's comedy:
"I appreciate the credit of being a mastermind, but I am a hard working wife, mom & comic. I barely have time 2 start my car"
Listen Amy Schumer on Jim Norton Advice Show: