What room does Tandy find herself in?

A boy's bathroom

Tandy was relieved to see that the room was empty, but that was about the only good news. She was in a boy's bathroom! Urinals lined one wall, with sinks opposite. A mirror was fixed to the wall above each sink, and Tandy caught sight of her reflection: a scared, naked girl, one arm thrown between her legs, and the other across her chest. Any boy that walked in would certainly have a pleasant surprise. Knowing that she wouldn't be alone for long, Tandy hurried over to a cubicle.

Bolting the door behind her, Tandy sat down on the toilet and pulled her knees to her chest, wrapping her arms around her long legs. The blonde started to shiver; yes, she was cold, but that was hardly her most pressing concern.

Sure enough, the bathroom door banged open a few seconds later, and Tandy could hear a number of boys moving about. She crossed her fingers: please leave me alone...

__*BANG BANG*

"Hey, hurry up in there!"

Tandy gasped: someone wanted to use her cubicle! If she spoke, she would reveal her gender; if she didn't they wouldn't leave her alone. Trying to adopt a deep voice, Tandy stuck a few fingers down her throat to make herself gag.

"I-I'll be a while..." she said, an octave lower than her usual pitch, praying that he would believe that she was throwing up.

Thankfully, he moved off. After about 5 minutes, a second bell rang, and the bathroom emptied. Distant footsteps faded, and finally silence fell. Tandy was alone.