My ten-year-old brother thinks tattoos are neat, so I'm going to have my tattoo artist friend give him one.
That is not good. Why would you let him get a tattoo?
I know it's not good, but I'm curious to see what will happen.
That is very irresponsible of you. Young children should not be given a permanent tattoo because they are too young to decide. You should let him get a fake one instead and see how he likes it.
I'm going to give him a real tattoo, it will fade in time.
Kids should not get tattoos. Your artist friend is unlikely to do it, because they would lose their license, and your parents would be very angry. Go with the temporary tattoo.