Xbooru - 2010s 2016 2d 2d (artwork) 3boys anal animated skeleton artist name bigger male bigger penetrating bigger penetrating smaller blue blush blush bottom sans brother penetrating brother brothers clothed clothed/nude clothed male digital media (artwork) fifithemantis fire elemental fontcest grillby grillby (undertale) grillsans heart eyes incest larger male larger penetrating larger penetrating smaller male male only male penetrating monster naked male nude nude male orange blush orange body papyrus papyrus (undertale) papysans penis in mouth pink background sans sans (undertale) seme grillby seme papyrus simple background skeleton smaller penetrated solid color background spitroast tears third-party source threesome top grillby top papyrus trio uke sans undead undertale undertale (series) video games yaoi