Tell him to come up with an idea for himself but that he has to sit on it for a year. If he still wants it after a year then it’s probably not just an idle fancy
I think that’s the line I was given when I was around 15 or so.. it prompted me to go out and get a cheap, shit tattoo in secret the following week..
The only real way around this is to get into it and get matching tattoos.. Traditionally they are tribal symbols, and you don’t get any more tribal than parent and child..
You’d be giving summink (sic) back to the tradition, bonding with yer lad and he’d end up maybe learning something about the history of tattooing and not perhaps ending up with a crap design..
Let him pick to start with but steer him down the road of something with a bit of artistic merit, negotiate, put some thought into your choice and get something that has meaning for both of you.. or get something bespoke.. research styles and then find a good relevant tattooist to do the work, find out about the historical symbolism behind certain designs etc
He might go off it by the time it’s all settled..