An ambulance, fire truck, police car, or other emergency vehicle equipped with sirens and flashing lights. Derived from the siren sounds, onomatopoeia.
1. Telling your friend/friends to stfu and stop whatever they are doing
2. Telling your horse to stfu and stop whatever it is doing
3. An exclamation for extreme disbelief
Man 1: So then i was like "OMFG" and then i was like "OMG HOW COULD THAT HAPPEN OMG OMG-"
Man 2: Wo wo wo! No! What the hell r u saying?!