I used to wet myself when I was doing long-distance bicycle riding. I wore bikini underpants, black spandex biker shorts on top of them, and black gym shorts on top of them. It was such an exhilarating feeling just letting go, and feeling that warm, wetness spreading inside my spandex biker shorts and soaking my bikini underpants. Since I wore black gym shorts, the wetness did not show thru, so nobody knew I was peeing as I passed them on the bike trail! Very erotic!!!
Also, sometimes, my mutual-masturbation buddy will wet my bikini underpants for me, and I'll wear them underneath my clot