Well, it depends. Am I getting shot at with little hope for survival? "Crap, crap, crap, crap, craaaaap!"
If I'm playing Bad Company 2 and someone blows up a piece of wall right in front of me? "GAAAAAH!"
Alternatively, if there's a bunch of dudes in a building and I blow it up? *demo-man voice* "KA-BOOOOOOOOM!"