English version comes after Japanese.
Oh my Godって映画などでよく聞くので、気軽に使うのかと思いきや、そう単純な話ではないようです。口癖のように使う人もいれば、形を変える人もいます。「Oh my gosh」とか「Oh my」で止めたり「my my my」とか言い方は様々。いずれにしろネイティブでない私たちが気軽に使わない方がよさそう。
If you hear a non-native English speaker say "oh my God" in Japan, please don't be offended. Those people simply use this phrase casually as they hear on movies or drama series. If you heard it from your friend, it'd be nice if you could tell him/her not to use it like a joke.