Yes, you check Stall 3.

Deducing that it came from the side closest to the third stall, you step out from behind the curtains. You lay down on your front and look under the curtain.

The reflection of a nerdy girl stands in the mirror, watching a video on her phone. A moan comes from the video- your moan. She seems to be blushing as she views it, a large bulge forming around her crotch area. You try to ignore the bulge and study her. She had white long hair and glasses, a hood over her head. She was wearing leggings similar to the ones you were, showing off her huge bulge more and more.

You stared at her, your cock growing as she sits down on the stall. Her phone continued to play the video of you masturbating as she started to rub her dick through the leggings.