2) abbreviation of the name of an anime/manga Oh! My Goddess, sometimes also known as Ah! My Goddess
3) abbreviation of "Oh my god", said by over-excited, shocked, horrified people.
2) Hey could I please borrow your OMG manga?
3) OMG!!! I just saw a flying pig!!!
Correct Response - "Speak proper, or STFU, N00B!"
Silent then proceeds to sock her in the face.
Simply put OMG means, Oh my god!
Person 2: "O M G. , have they even heard of the word fashion."