The act of filling a toilet bowl with a large amount of toilet paper and then proceeding to defecate onto it, thus causing the turd remain afloat. The feces surrounded by toilet paper symbolizes Baby Jesus wrapped in blankets in his manger. The poop manger is then left there for the unsuspecting victim to encounter.
"I sure showed those guys."
"What did you do?"
"I snuck into their bathroom and left them a poop manger, poor bastards never saw it coming. I'd hate to be the guy to clean that up."