Xbooru - 2010s 2017 2boys anal animated skeleton bed bedroom black legwear blue blush blue tongue blush bodily fluids bottom sans bottomless bottomless male brother brother/brother brother and brother brother penetrating brother brothers closed eyes clothed clothing doggy position door duo ectotongue english text fluids fontcest from behind position hooded jacket hoodie incest indoors jacket legwear male male/male male only male penetrated male penetrating male penetrating male monster motion lines mounting on bed orange blush orange tongue papyrus papyrus (undertale) papysans partially clothed partially clothed male penetration penetration from behind sans sans (undertale) seme papyrus sex sex from behind skeleton spookster text thrusting tongue tongue out top papyrus topwear uke sans undead undertale undertale (series) visible breath yaoi