Xbooru - 2020s 2023 2boys animated skeleton big penis bigger dom bigger dom smaller sub bigger male blush blush lines boots bottom sans brother brother/brother brother and brother brothers clothed clothing duo ectopenis erection fontcest gloves hooded jacket hoodie huge penis imminent penetration imminent sex incest jacket larger male long penis male male/male male only monster monster cock monster penis nervous off shoulder papyrus papyrus (undertale) papysans penis penis out purplebluepen45 sans sans (undertale) seme papyrus sequence sequential sitting size difference skeleton small sub small sub big dom smaller sub smaller sub bigger dom top papyrus uke sans undead undertale undertale (series) veiny penis yaoi youfoundta