Display
You're in prison, but you can use your fingers and a spoon in the light of the sun to display little moving pictures on your cell wall. It's like a shadow puppet display except you can only make a few characters with your limited hand tools.
Imagine displaying your two favorite characters in the shadows on your prison cell walls. This one is mister fingers and this one is missus spoon. They're best friends.
けい
かか
None
There is one thing you display more than anything else and it's cake (けい). You smush your fingers to make a cake shape and use the spoon to pretend you're eating it.
Imagine displaying cake on the wall. Now pretend to eat the shadow cake with your spoon. You can almost taste it. Except you can't, because this is still prison.