Well, a British person would say God, but seeing as it's pretty OOC for Hermione to say that anyway, I think you're best of having her say, "Oh, Merlin, that hurts!" or something similar.
Jeepers is American, and crap, although we English do say that, is considored American on MNFF.
~Evie

I remember that in Deathly Hallows Hermionedid say "God" a couple of times but is probably more likely to say "Merlin's beard" or something. 




