"Scotty Doesn't Know" was written for the film by the band Lustra. It's kind of taken on a life of its own, due in no small part to its hilarious premise -- the lead singer of the band is singing a song about fooling around with Scotty's girlfriend, Fiona, and describing things in excrutiating detail. It's kind of nasty, and hilarious. The fact that Matt Damon's lip-sync'ing it all while pierced to high heaven is icing on the cake. We spoke with Lustra's guitarist, Nick Cloutman, about writing the song and Matt Damon singing for them.