Not exactly the option you thought you pick, but what with it being more private of a place than the rest of the building it's seem fitting.

Shame though, this place had seen better place, a few graffiti and doodles that are half washed and some grime here and there. Yet it's one of the most modern bathroom to boot. And quite large than your bathroom, enough to fit 10 people for a stall of 8.

You went into a random un-occupied stall. Seeing as no one's here, you could shrink yourself, unlock the stall and wait for someone to come.

There's also two phone number here, one on the side and another with a glory hole below it. Both with the same message.

"Wanna hook up? Call here:" Very straightforward.