Let's start with the ending: the closing credits disclaimer that insists that none of the lead actors in Lars Von Trier's Nymphomaniac filmed penetrative sex. If there is real sex in the movie, and it sure looks like there is, it must have been done by one of the eight credited sex doubles, listed far down the crew after the cast, somewhere around the caterers and gaffers. (Humble billing, but oh what luscious names -- my favorite was Elvira Friis.) The sex doubles loaned their loins to Von Trier, who digitally stitched them to his actors. In the era of Google image search, the difference between an XXX freeze frame of an actor having sex versus a perfect simulacrum seems technical at best, though I suppose their parents must be relieved.