The oldest kid I have seen in just a diaper with no other clothes other than shoes was a boy who looked to be about 8 years old.
I was in another town last Saturday when I drove by a house and 2 boys were outside playing in the backyard in the sprinkler.
A boy of about 3 was wearing a Pampers Baby Dry diaper and the other boy who appeared to be 8 years old was wearing a Pampers Cruisers size 7 I believe.
They both were wearing nothing but the diapers and shoes.
I could not see anything wrong with the 8 year old boy who was in diapers although sometimes you cannot tell someone has a disability or he may have been incontinent.
Or he could've had autism and was a late potty trainer or had bladder issues as a result of the autism.
I was so happy to see that boy out enjoying himself without a care in the world and able to wear just his diaper and shoes.
I ran around this summer in my fenced in backyard with just a diaper and shoes and sometimes just the diaper.
I wish I could do it in public but sadly cannot.
I also remember now seeing a boy of around 6 at a splash pad who appeared to have autism wearing just a Pampers baby dry diaper and a shirt and his sandals.