Xbooru - 1:1 1:1 aspect ratio 2010s 2016 2boys 2d 2d (artwork) ahegao ambiguous penetration animated skeleton big dom big dom small sub bigger dom bigger dom smaller sub bigger penetrating bigger penetrating smaller blush bottom sans brother brother/brother brother and brother brother penetrating brother brothers closed eyes clothed clothed male clothed sex clothing digital media (artwork) duo eli-sin-g fontcest gay gay sex heart-shaped pupils heart eyes hoodie incest jacket kolesjoie larger penetrating larger penetrating smaller leg lift legs legs up male male/male male only male penetrating monochrome monster onomatopoeia pants down papyrus papyrus (undertale) papysans penetration sans sans (undertale) seme papyrus sex shirt skeleton small sub small sub big dom smaller penetrated smaller sub smaller sub bigger dom sweat sweatdrop text third-party source thrusting into ass tongue tongue out top papyrus uke sans undead undertale undertale (series) upside-down upside down video games white background yaoi