I attended one once, thats where I learned the frozen half gallon milk crate trick. It was in the summer and they got a bunch of empty half gallon milk containers, filled it halfway with water, froze it, and peeled the cardboard off. It provided endless entertianment! I think if they handed out bones it might start trouble but it was SO funny to see a dog try to steal a huge block of ice, another was trying to protect his and push it to the edge of the lawn, a couple were scooting them around and one just laid on top of his, it was great and it obviously dosnt leave a mess!