Xbooru - 2010s 2017 2d 2d (artwork) 4boys animated skeleton blue blush blue tongue blush bottom sans clothed clothing cum cum in mouth cum on tongue ectotongue fangs finger in mouth fontcest gaster gaster (undertale) grillby grillby (undertale) grillsans hand implied incest lowest-of-dirt lowest of dirt male male/male male only monster multiple boys one eye closed orange cum orange penis papyrus papyrus (undertale) papysans penis red background sans sans (undertale) sanster seme gaster seme grillby seme papyrus skeleton solo focus tongue top gaster top grillby top papyrus uke sans undead undertale undertale (series) unseen character unseen male unseen male face upper body video games yaoi