Cow bingo is a game played by rednecks and farmers. They mark the ground to divide it up into bingo-like squares. Then let cows roam around the area, when a cow drops a "cow patty" (ie: takes a shit) the person who owns the square it lands on wins a prize (not the cow patty :O).
Announcer: It's been a hot day in the South for Cow Bingo today!
Announcer: Looks like Betsy just planted a cow patty on A4.
Cletus: Yee-Haw!!! That's ours! We's eating good tonight Claudine!!!