I practice all the time, sometimes on napkins while waiting for food to be served, and I will even draw silly characters on the receipts as part of my tip (which is almost always generous anyway).

If the server did something I specifically liked,the character will tell them. If the server made a critical error that affected their tip, I let the character tell them that too. One place, the server neglected my drink for a very long time, so I drew Alpsie there collapsed in a wasteland with a vulture perched on his shoulder ans a shriveled cactus nearby.

It's fun,and it's silly, and places we eat frequently remember the drawings, and tend to us I think perhaps a little more eagerly than they might if they hadn't had reason to remember.

This is just an example of such a sketch. I am gonna be including a few more of my rough sketches because it's helpful for others to see kind of the framework I use in "building" my drawings.

This is a picture of a younger version of Alps, or perhaps any other wolf, since there's not enough detail to really peg him as someone in specific.