I enjoy wetting--especially in disposable diapers, as they get that wonderful squishy feeling. In all the years since I was potty-trained, however, I've never messed a diaper. I consider myself a fairly adventurous person in general, but my curiosity about messing continues to be overwhelmed by my disinterest in dealing with my own poop. I have two potty-trained children of my own. I'm glad to be done dealing with the poopy blowouts!
But, for me, diapers are mainly an accessory to masturbation. They're a sexual fetish. It's hard to explain what that means, exactly, and it's different for all of us. I simply find the idea of myself as a diapered toddler to be an enormous turn-on. It's a variation on diaper fetishism that's also sometimes called autonepiophilia.