L.E.
Hi M.,
Try buying wet wipes the are easy to use and they are flushable to you could also tell him that he could get an infection from not wiping his bottom and he will get really sore and chapped . Tell him the wet wipes are there for him and he will get a reward if he can go a week using the wipes and not messing up his clothes, let him pick something fun he want to do if he does use them.. I have two boys and I know they can be real nasty one is 13 the other is 14, so don't think it is something you have done wrong or you missed it's a boy thing.. GOOD LUCK!!!