Gorgeous Jennifer Garner stopped by The Late Show with David Letterman to promote her latest film Arthur, but talk quickly turned to co-star Russell Brand's anatomy.

When asked about a certain scene in which she's on all fours with the British comedian, Garner tells Letterman:

    "He was in his underwear, and they were very handsomely made. It was Russell and me, right behind him, on all fours. We did it over and over again, so I spent two days just right up against it. So I'm very familiar, in my own way, with the anatomy of Russell Brand -- and it's good."

Not sure how hubby Ben Affleck is handling that one. The dimpled 38-year-old cutie also tells Dave about her unusual job in college. Find out which job that was ... after the jump.