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"Scotty Doesn't Know" is a song that was written exclusively for the movie EuroTrip. It is performed by the band Lustra (although commonly mis-credited to the band Sum 41), but in the movie, the lead singer was portrayed by Matt Damon, whose character has surreptitiously stolen a girl from "Scotty," hence the title and subject matter. The song contains numerous lewd references to how Scotty's girlfriend Fiona (played by Kristin Kreuk) has been cheating on him with Damon's character for an extended period of time.