Xbooru - 2020s 2022 2boys anal animated skeleton big dom big dom small sub big penis bigger dom bigger dom smaller sub bigger male bigger penetrating bigger penetrating smaller blue blush blue hoodie blue jacket blue penis blush boots bottom sans bottomless bottomless male brother brother/brother brother and brother brother penetrating brother brothers duo ectopenis ectoplasm fontcest gloves hooded jacket hoodie incest jacket larger male larger penetrating laying on side lying on side male male/male male only male penetrating monster motion lines on side papyrus papyrus (undertale) papysans partially clothed partially clothed male penetration penis penis size difference red boots red gloves red penis s2ames2 sans sans (undertale) seme papyrus sex sex from behind size difference skeleton small penis small sub small sub big dom smaller penetrated smaller sub smaller sub bigger dom socks thrusting top papyrus trembling uke sans undead undertale undertale (series) white background white socks yaoi