This is a question that I found and answered on quora.com last year however I have posted it here so anyone can read it.
Question: is it okay for an adult to wear a diaper/nappy just for fun?.
My honourest answer is yes although, in my opinion its entirely up to you what you wear and as long as your not breaking any laws or hurting anyone why the heck not.
In fact only last year in June of 2020 I was at home wearing a pair of Abu Simple Ultra's in large, they were very comfortable and also very absorbent.
See my previous review for more information
In my opinion diapers/nappies are just another form of underwear that are more convenient to change in and out of when needed.
There's absolutely nothing wrong with wearing them weather it's for a genuine medical condition/disability be it physical or psychological or just for fun in some cases
I think people that don't understand this should in themselves grow up to the fact sooner or later everyone needs them and it doesn't matter if your a baby/infant as in bellow the age of 5 or if your a adult in his 20's or older in my case as I am 41 later this year in October.
The whole ridicule/stigma thing needs to change once and for all as no-body deserves to be made fun of or bullied just because of what they wear as specially as it constitutes a form of discrimination against the disabled.
As no body has the right to prejudge any-one if you aren't committing a crime then you should be left alone.