Xbooru - 00kaori00 2boys 2d 2d (artwork) animated skeleton big dom big dom small sub bigger dom bigger dom smaller sub blue blush blue eyes blue penis blue tongue blush bone bottom sans bottomless bottomless male clothed clothing digital media (artwork) duo ectopenis ectotongue frottage frotting gay hair over one eye humanoid robot larger male male male/male male only mettasans mettaton mettaton ex no background outercourse penis penis on penis pink eyes pink glans robot robot humanoid sans sans (undertale) seme mettaton sex sitting skeleton small sub small sub big dom smaller male smaller sub tears tongue tongue out top mettaton transparent background uke sans undead undertale undertale (series) video game character video games yaoi