Xbooru - 13thcatofthegate 2010s 2018 2boys 2d 2d (artwork) 2males anal animated skeleton bigger male bigger penetrating bigger penetrating smaller blue blush blue penis blush bottom sans brother/brother brothers comic comic page comic panel comic sans completely nude completely nude male digital media (artwork) duo ectopenis english text fontcest gay genitals hugged from behind hugging hugging from behind incest indoors larger male larger penetrating larger penetrating smaller looking at another looking at partner male male/male male only monster naked nude nude male orange blush orange penis papyrus papyrus (undertale) papysans partially colored penetration penis sans sans (undertale) seme papyrus sequence sequential sex shorter male skeleton smaller male smaller penetrated speech bubble taller male text text bubble top papyrus uke sans undead undertale undertale (series) undressed video game character video games yaoi