I am not sure if I ever really noticed the arrows on the S and Y. But the girls obviously have. When we play pictionary, we often use the box with the sign on top to represent a store. And notice she didn't use letters but the squiggles were for the SUBWAY letter on the top of the sign.
I would have been just wasting my time drawing some kind of an underground train. Thanks for playing along. I would have been very surprised if anyone guessed it. I thought this was a fun idea for a post.