We had some barn cats with kittens several years ago, and one of the kittens discovered his reflection on a chrome bumper. He'd put his paw up close to the bumper (which made it look huge), then hurriedly back off, then slowly approach and do it again.
I don't know how long he'd been doing it when I first saw him, but I watched him for several minutes, and he was still doing it when I went back to the shop.
If you want to see something funny, put out some fermented jelly for the cats to eat. Mother-in-Law threw some away one time and the farm cats were definitely feeling no pain.