Xbooru - 2010s 2018 2boys 2d 2d (artwork) animated skeleton ass ass up bed bedroom big dom big dom small sub big penis bigger dom bigger dom smaller sub bigger penetrating bigger penetrating smaller blue blush blue pussy blush bookshelf bottom sans bottomless brother brother/brother brother and brother brother penetrating brother brothers digital media (artwork) doggy position doggy style position duo ectopenis ectopussy fontcest from behind from behind position genitals gloves incest indoors larger penetrating larger penetrating smaller male male only monster nsfwgarbagedump on bed one eye closed orange blush orange penis papyrus papyrus (undertale) papysans partially clothed penetration penetration from behind penis pixiv id 36285069 pussy red gloves sans sans (undertale) seme papyrus sex sex from behind sex on bed skeleton small sub small sub big dom smaller penetrated smaller sub smaller sub bigger dom top papyrus uke sans undead undertale undertale (series) video game character video games yaoi