Greek slang (and pronunciation) meaning things ALONG THE LINES of "what the heck?" or "oh my gosh"?

I don't expect or want a direct translation of those phrases but just like slang phrases (in Greek) that are used in the same way as those phrases. (please give pronunciations as well) if you have any in other languages besides Greek feel free to give them as well...that'd be great. Please help quickly! GOD BLESS!