The pup, in his singlet, can't hide his excitement. His tail stands rigid, tenting the fabric. He tentatively slips a hand inside, wrapping it around his throbbing, uncut cock. He strokes slowly, savoring the sensation, his breath hitching as he picks up speed. His other hand reaches down, cupping his heavy balls, rolling them gently. His imagination runs wild with scenes of other pups servicing him, and he can't hold back any longer. With a grunt, he comes, his cum splattering onto the singlet, marking his territory.