Okay but like can anyone can explain to me if this is actually safe? Like playing and putt...

Okay but like can anyone can explain to me if this is actually safe? Like playing and putting food up the butt or genitals area seems sort of unhygienic - won’t there be a spread of something? I’m actually concerned coz I see this in other mangas as well but I just hate to imagine the stickiness and smell from the mix of everything it seems nauseating.