I vote for 'dang'. Can't go wrong with 'Dang, McKay, inappropriate much?'. It's so useful - 'Dang, those Wraith are annoying!', 'Dang, my sweater is unraveling!', 'This sure is one dang fine day!'

...hahaha, I jest. I don't really suggest dang. But it was amusing for me to imagine it for a minute.

Sadly, I don't have a real suggestion.