One of the most popular games with my children was to write on the child’s back, and have them tell me what I wrote.
It starts really simple, like writing an “A” or an “O”. Then I’d draw some symbols like a plus sign, a box, a triangle, or even a tree.
Then more challenging was writing a word or a phrase.
This is really fun, sensing what someone is writing on your back. It could be your arm or leg, too. But we used the back.
We would reverse roles, too. And I would guess what they were writing.