An abbreviation for the commonly used phrase 'Oh My God'. Newly pronounced as "oh-ma-gox". An impressive way to start your online chatting sentences.. or not.
The "x" stands for hardly anything, just some letter to make things look cooler.
Gedik 12: I saw Jason Mraz live the other day!
Gedik 8: WHAAAAAAT? OMGX! Seriously dude?!