I think "OMG" is commonly use in our daily life, anything, we will go "OMG, OMG". You agree?
Lately when i said "OMG" i have to careful, i make sure i use the correct term. I use to said "oh my god!".
One day, my boy told me, "mummy, you know you cannot said "oh my god", you got to said "oh my gosh" or "oh my goodness", because you cannot use "god's" name! @..@
Oh ya, my two boys are in a christian kindy, that's why they learn a lot from there. :)