A traditional nappy.
Not much choice, really, as I'm smeared in my homemade cream, to help soften the stonking zit on my arse. Once dampened enough (the cream becomes active and disinfecting when moistened), I'll be off for a good scrub.
And as it's a summery 15°C, I'm wearing some cheap, badly designed plackies which allow the nappy to poke out; this helps keep things cool (through evaporation).