What does the casting director mean by "be authentically, anatomically not Jewish" in Friends?

Question

In the Friends episode The One With Ross and Monica’s Cousin, Joey auditions with a casting director; the plot is as described:

The Casting Director: Terrific! Well uh, there’s one more thing. Uhh, uh it’s really important to the director that everything in this movie is authentic. Yeah and so in your love scene with Sarah she talks about how she’s never seen a naked man who wasn’t Jewish. So… (Laughs.)

Joey: So…What?

The Casting Director: So uh well the director is insisting that whoever play that part be authentically, anatomically not Jewish. Do you know what I’m saying?

Joey: Yes!

The Casting Director: Okay.

Joey: No. What?

The Casting Director: An Italian Catholic immigrant at this time would not be…

Joey: Bar Mitzvahed?

(The casting director shakes her head.)

(Joey thinks about it and finally realizes what she means.)

Then later at Monica's apartment

[Scene: Monica and Chandler's, Joey is telling Monica what the casting director was trying to get too.]

Monica: So to get this part you can’t be?

Joey: Nope.

Monica: But you are?

Joey: Yep.

Monica: But you told them you weren’t?

Joey: That’s right.

Monica: Wow! Wow! And it’s definitely all gone? There’s nothing there to work with? (Joey glares at her.) What were you thinking?

Am I missing something here? What exactly does the casting director mean?

Answer 1

They mean his foreskin. Joey has been circumcised, which means his foreskin was removed when he was young. Thus, he and Monica try to fashion a fake foreskin so he can portray an uncircumcised man, a plan that ultimately fails.

Though Joey is a Catholic Italian, circumcision is a common global procedure and it is estimated that 30% of the males in the world and around 55% of the males in the U.S. are circumcised.