The man's kinky fantasy unfolds as he fills his nappy, the piss soaking through the material, creating a damp, sticky patch. He wriggles, enjoying the sensation of his own waste contained within the diaper. His cock, now rock hard, tents the front of the nappy. He strokes it, the wetness adding a slippery, taboo element to his masturbation. The nappy, now heavy with piss, droops between his legs, a constant reminder of his naughty deeds. He fucks his fist, imagining the nappy filled with cum instead of urine, before finally erupting, adding his load to the mess within.