The phrase originated in the backwoods of Maine. "The Scrooched Moose" is the act of wildly thrashing about as you rapidly change through sexual positions. If at a campsite the scene left behind will look as if a wild bear ransacked your tent. If indoors the scene will look as if you had been burglarized.
A man at the bar was bragging to his buddy l; "Hey man, last night I finally got The Scrooched Moose treatment.".