1) Poop in the water game
This will test your coordination and spatial abilities. Horses all over the world practice this, every day. You must try to poop in your water container (note: drink water first, so you won't go thirsty!). If your water container is too high to poop in, you can attempt to poop on the stall's door, or on the wall. This also gives your human something to do-- when they see what you've done, they will marvel at your special abilities, then happily provide you with fresh water.
2)Pee in the water game
A real challenge for geldings and stallions! Attempt to pee in your water container. This is a very challenging game. If your water container is up against a wall, you may try to drag it into the middle of your stall. Either way, be sure that you've mastered #1 above first... so your human knows to provide fresh water for you!
3) Artistic Wood Carving
You can become a wood carver. Use your teeth to chisle the wood of your stall into a beautiful piece of art! At first, you can start with simple shapes -- such as the half-moon bite shape-- and as you become more advanced you can try different forms (big curve shape or multiple bite shapes). Your human will really appreciate this.
Some humans will actually remove your artwork from the stall, and put up fresh, new, unchewed boards-- encouraging you to develop your artistic abilities with a fresh, new canvas!
4) Grain Spilling Game
Try to dump out all of your grain from your grain bucket/container, by turning it over with your nose. It is a fun game. You can even continue to flip the container to be sure that all the grain is dumped on the ground. Then, using your delicate muzzle to guide you, try to pick up all the grain, sorting throught the bedding and poop. Amusing, and it makes your grain last longer. Your human will appreciate it too-- he/she may even bring you a new bucket of grain, or challenge you to become better by using more difficult containers.
5) Hay Dunking
In this game, you'll try to grab a bite of hay, carry it to your water container, and dump it in. Dropping hay in your water is fun for both you and your human! Although it's just hay, they will probably come in your stall and remove it from your water (then you can dump more in).
6) Who Can Be The Loudest
If you're stalled with other horses, try a little friendly competition with this game. When it's feeding time, see who can neigh, bang, scream, and kick the loudest in their stalls. Humans will instinctively throw food to the noisiest, most demanding horse, so try to be it. The winner is the horse that the human feeds first.
7) Smoosh The Bedding
In this game, you can attempt to mix your bedding, poop, and hay all together. You do this by walking all around in your stall, until you get a good, even mixture. Some horses walk in circles, or back and forth in a straight line... experiment with different styles to see what you like best. Again, this provides entertainment and excersize for your human, because they will have to clean it all up.
8) Roll in the stall
Attempt to get a good roll, in your stall. If your stall is big, this is easy; however, the smaller the stall, the more difficult it can become. The object is to roll, well, without getting stuck. There is some danger involved in this game, as you could roll up near a wall and get stuck (but then, your human will rescue you-- be sure to do this near food time just in case!).
9) Mane Rubbing
Try to rub your mane out in certain spots. Humans like neat manes. That is why they comb, spray, and pull your mane; Save them work by pulling your mane yourself! You can stick your head through the stall (if it has an opening) and try to rub the top of your neck. Or, just rub it on the side of a wall. This will give your mane a nice look that humans appreciate (clumps of hair missing). You'll save them time on having to pull your mane or trim a bridle path.