I just discovered this earlier tonight... sorry if hoards of people have already discovered this fun-ness, but I searched briefly and didn't find any other threads about it. So anyways....
1. Get a tennis ball
2. Either wait until your pup "kills" it or go ahead and step on it yourself (not lightly) until it POPs. Either way, the ball needs to have a split down one side.
3. Open the ball up like one of those funny little plastic change purses, and dump some kibble/carrot bits/etc. inside.
This entertained Nikko for a good half hour tonight, and he only got a 5-6 kibble bits out of it, so he'll probably go back to playing with it tomorrow again too when he feels hungry and feisty.
- Lauren & Nikko