Xbooru - 2010s 2015 2boys 2d 2d (artwork) animated skeleton big dom big dom small sub bigger dom bigger dom smaller sub black hair blue blush blue penis blue tongue blush bottom sans digital media (artwork) ectopenis frottage frotting groping hair over one eye humanoid robot male male/male male only mettasans mettaton mettaton ex outercourse partially colored penis penis on penis pink penis pleasure face pleasured face robot robot humanoid robotic penis sans sans (undertale) seme mettaton shirt lift shirt up skeleton small sub small sub big dom smaller sub spoopy-latte third-party source tongue tongue out top mettaton uke sans undead undertale undertale (series) video games yaoi