Xbooru - 2010s 2016 2boys 2d 2d (artwork) animated skeleton bigger dom bigger dom smaller sub bigger male black body black penis black tentacles blue blush blue body blue penis blue tongue blush bottom sans bottomless clothed drooling ectobody ectopenis ectoplasm gaster gaster (undertale) goo grabbing chin grabbing face grabbing own penis gradient background grey background half-closed eyes holding own penis hooded jacket hoodie jacket larger male male male/male male only maledom malesub partially clothed partially nude penis precum safetytrance sans sans (undertale) sanster skeleton small sub small sub big dom smaller male smaller sub smaller sub bigger dom sweat tentacle tentacle on male tentacle under clothes tentacles tentacles around arms tentacles around legs tentacles on male tongue tongue out uke sans undead undertale undertale (series) video games yaoi