Xbooru - 13thcatofthegate 2010s 2018 2boys 2d 2d (artwork) 2males all fours anal animated skeleton bigger male bigger penetrating bigger penetrating smaller blue blush blue cum blue eye blue penis blue tongue blush bottom sans brother/brother brother penetrating brother brothers comic comic page comic panel comic sans completely nude completely nude male cum cum on sheets cum while penetrated digital media (artwork) doggy position doggy style position drooling duo ectopenis ectotongue ejaculation english text fontcest from behind position genital fluids genitals glowing eye handjob handjob while penetrating incest indoors larger male larger penetrating larger penetrating smaller male male/male male only male penetrated male penetrating male penetrating male monster nude nude male orange blush orange eye orange penis orgasm papyrus papyrus (undertale) papysans partially colored penetration penetration from behind penis sans sans (undertale) seme papyrus sequence sequential sex sex from behind shorter male skeleton smaller male smaller penetrated speech bubble taller male text text bubble tongue tongue out top papyrus uke sans undead undertale undertale (series) video game character video games yaoi