The Goodfellas star portrays 1970s X-rated actress Dolly Sharp in the film, Lovelace, and when directors Rob Epstein and Jeffrey Friedman were picking out extras to join her for a saucy sex scene she suggested her partner Gabriele Corcos would be happy to jump in.
Mazar tells Paper magazine, "There was a direct scene from the actual Deep Throat (porn movie) and I asked the director, 'Who's gonna be the guy that's going down on me?' And he said they were just going to get an extra, so I was like, 'How about my husband? He's really cute'.
"He wasn't '70s-looking enough, so they gave him a '70s wig. At least I felt comfortable with him down there, and he's really proud because he gets his first movie credit."
Mazar admits she was puzzled when she first learned Epstein and Friedman were keen to cast her as Sharp - and she wishes they'd have taken her character further, because she was willing to get naked for the film.
The actress adds, "I thought it was going to require some nudity, so I grew out my b**h (pubic hair) - because I figured, 'It's the '70s - and my armpit hair. But then I got to work and I realised it would be covered up. I was ready to try to really be authentic and it wasn't necessary."