Tatum O'Neal On The ONE Word She Refused to Say On Denis Leary's "Rescue Me"

Denis Leary's post-9/11 dramedy "Rescue Me" was without a DOUBT an R-rated show that had no problem going there, if you know what we mean.

But the one word that broke (youngest Oscar® winner ever!) Tatum O'Neal, who played Denis' on-screen sister, Maggie, on the long-running FX series?

Well, we'll let her explain it!

"I play [Denis'] sister," Tatum explains, "and I'm a rough alcoholic — I'm that girl — and I smoke a lot of cigarettes and stuff. And [one day] he goes, 'Tates! Tates, so I've written this scene… You know what a ***** is?'"

Turns out, she was stumped!

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"I'm not Maggie Gavin," she notes, laughing. "I'm Tatum, and I'm super weird and prude-y, and don't know what that is! And he goes, 'You know, *****! It's that place between where you p** and where you...'" And she points behind.

I think you know what she means!

Well, Tatum was not having it. "I said, 'Oh, Denis! I have kids, I can't say that! I would never say that!'"

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That's when Rach LOST IT!

Watch them laugh it out in the video above!