A school bathroom is a horribly disgusting place. There is a ton of graffiti, stall doors that don’t lock, the stall itself has crap everywhere, some idiot peed in the sinks and they are overflowing, and used toilet paper is strewn about.
The place where people go to relax, be themselves and spill tea. Awkward if you ever use this holy place to pee and someone else is there using it for its spiritual powers. If you are invited to the school bathroom you are automatically cool and that person trusts you.