Sans

you came into the skelebro’s house after a long day of work, throwing your coat on the rack and flopping on the sofa. Soft sounds were coming from upstairs. Papyrus is with Undyne for a sleepover, so that means it’s Sans. What is he doing? You walk up the stairs to Sans’ bedroom, carefully and quietly opened the door. Through the thin slit you see Sans masturbating on his mattress