Wait for someone to show up

You wait awkwardly for a few moments, twiddling your thumbs, checking through your social media for anything of note, playing a boring mobile game that's mostly just watching ads...

Finally, you're stirred out of your boredom by the sound of the door opening across from you, in the adjacent stall in the girl's room. You peek your eye through, but the person's already entered the stall, giving you only a glance at the grey fabric of the school uniform.

Not able to see who's on the other side makes you nervous, but certainly arouses you. Given how horny the girls are here, you doubt they'll turn down a chance at easy dick, though, but there's always a chance they'll react badly.