I second explaining the Nip/Tuck episode to her, obviously she didn't pay much attention.
I also agree with showing her the function of the foreskin etc, and then showing her an adult intact male naked in a movie (since she likes TV). Innocently rent the movie, ask her to watch it and when he's naked go "Oh wow, he's not cut" or something similar.
Then the circumcision videos. Then the testimonials of pissed off men who want their foreskins back.
And then ask...