Yes I have worn a diaper on a roller coaster before.
It's a good feeling wearing a diaper on a roller coaster and if I need to pee during the roller coaster ride I can do so.
It was also a good Idea last year I wore a diaper on a roller coaster as I did get scared enough that I peed my pants or well I peed my diaper.
I would've peed my pants had I not had a diaper on.
I've always worn diapers to theme parks, fairs and other outdoor gatherings.