or cooled off on a hot summer day: get a big plastic container - large tub of yoghurt or even the big tub of ice cream. drop a few treats (anything - biscuits, raw food, whatever) in the bottom and add about 1-1/2 - 2 inches of water or broth (or for more fun, alternate layers of water and broth). freeze. repeat until the tub is a solid block of ice with treats frozen throughout (if you put all the treats in at first, they'll either all sink at the bottom or all float to the top). put outside with the dog and never hear from him for about an hour or so.