From the A.L. Tribune:
WELLS — A few years ago it was illegal. Cow plop bingo returned to Kernel Days in Wells after event organizers learned it was legal with stipulations. In cow plop bingo, a cow grazes of an area divided into boxes, and the object is to pick the square the cow does its business onto.
The Wells Chamber of Commerce board received a letter from the Minnesota Gambling Control Board after the event in 2006 stating such gambling was not allowed because participants could sway the animal toward a square. “We just got a letter warning us that can’t be done because it’s not a game of chance, so to speak. They thought the potential for manipulation was there,” said Rick Herman, who was on the chamber board at the time. More here.