At some point last year I subscribed to e-mail updates from Box Office Mojo, thinking that weekly box office results was information I should be regularly privy too. Needless to say, I was bored after the first few weeks. On one occasion, though, the e-mail had a link for a list of the top grossing NC-17-rated movies of all time. Now this was fun information. Showgirls was at the top of the list —