Cowflop Bingo is a raffle activity that is enjoyed at many rural county fairs, picnics, and the like.
To play, you'll need:
Tie the rope to the halter, and stake down the rope. This is so the cow will not wander off and scare a soccer mom. Put the water within reach, so Bessie doesn't get thirsty. Using the chalk dust or spray paint, mark off a grid on the ground, say, 15ft by 15 ft (5m by 5m). You should have the grid be 5 squares by 5 squares. Number the squares.
Sell tickets to the eager audience. Each participant picks a square, and write the number of the square on both copies of the ticket. If you have more than 25 people, the winner(s) will have to split the prize.
The players spend the time filling up on potato salad, hot dogs, and other standard picnic fare. Meanwhile, the judge of the contest keeps an eye on Bessie. When nature takes its course and Bessie lays down a cowflop, note which square it landed in (or mostly in, if splattered, and beleive me, they will), and announce the winner.
Patience is required. It typically will happen in 1-3 hours, but sometimes it does take all afternoon. Please note that it is a really bad idea (not to mention cruelty) to feed a cow a laxative.