I suppose one way to think of it is the pairing/"ship" of Junko (the kitsune bit with her "spirit?" tails) and reisen (udon"ge") in a bowl. Whether that was the intent of the one who put it in the pool or not, who knows...
Junko's name is written as 純狐 which literally means 'pure fox'. 狐うどん is a type of udon and perhaps one of the reason why people pairs these two since the shipping abbreviation is hilariously fitting.