I don't have any tattoos. If any of my 3 kids plan on getting one, they better count on marrying someone rich. There's a clause in my will that states that after I die, all three of them have to have an examination by two independent dermatologists who have to certify them tattoo free. Any heirs determined to have a tattoo(s) will be written out of the will and the money gets split by those who don't. If all 3 have tattoos, the money is placed into a trust for their children if they ever have any, to which the same rules apply.
It's an amount in the low 7 figures so a bit of a motivator.