The interjection is also known to be a good palliative to heart attack when seeing unexpected unpleasant thing.
However it didn't work for OBL. He used it as a spell against the team six guys who got in his basement: " Get the fuck outta here!" but he get shoot anyway. The team six guys appeared to be deaf dumb both.
It simply means that you don't believe what someone else said.
Mikey: Get the fuck outta here! What are you, nuts?