19 Awesome Movie Cameos Nobody Saw Coming
11. Matt Damon - EuroTrip
Cameos don't get much more surprising (or awesome) than this. After protagonist Scotty (Scott Mechlowicz) gets dumped by his beautiful girlfriend Fiona (Kristen Kreuk), he attends a house party where the band's lead singer, Donny (Matt Damon) starts singing a song dedicated to "the nastiest, freakiest little sex puppet", referring to Fiona.
That's not even the best/worst part: he then tells Fiona, "Happy anniversary", before launching into the bewilderingly catchy tune, "Scotty Doesn't Know", which is all about Scotty's own ignorance that Fiona was cheating on him with Donny.
Damon, shaved head and all, fully commits to the part, and only appeared in the film by chance, because he was shooting The Brothers Grimm nearby in Prague, when his college pals (who wrote EuroTrip) asked him to appear in their film.
It's easily the best part of the movie and all the proof you need that Damon doesn't take himself too seriously. Just wonderful.