The guilt is consuming him from the inside out, yet he can't bring himself to stop until he cums. Maybe until he's cum multiple times to the thought of mama and the things he wants to do with her. One day someone calls him a motherfucker as a general insult and he locks himself in his bedroom and has himself a guilty jerkoff session until he passes out, cum all over his hand and the sheets. Probably sobbing as he humps a pillow pretending he really is a motherfucker.