I'm really surprised by how many people are upest by this. I think it's hilarious, especially with what the tattoo was of. I do agree that it wasn't humane, but really people? as long as you take care of your cat it will live long and happy for a long time. cats can't see colors and the pain of it would go away after not too long, so all-in-all the cat will forget it ever happened.
Though I do think it's sad that the cat will be gawked at and man-handled so people can see his tattoo.
But people who do things like this for amusement should be careful with who they go to for the tattooing, because doctors aren't as careful with animals and sometimes they die from too much anaesthesia. It happened to my Dad's parrot and he's still bitter about it after about 15 years. Please be careful with their safety.