They hear noises from the next stall

In the quiet of the next few moments, Leigh realizes she can hear something happening in the next stall. It isn't much, and it takes Leigh a moment to realize what it is. Heavy breathing, and, every once in a while, a wet sound. She looks down at Avery, whose smiling mouth is kissing Leigh's labia, and Avery nods, confirming her suspicions.

The woman in the next stall is masturbating.

A moment after the light bulb realization, Avery is back at it, now unabashedly slurping up Leigh's juices. There is no longer anything surreptitious about her movements as she slams Leigh's ass against the stall wall and lets out muffled moans into her pussy as she finger-fucks herself. Leigh continues to struggle to stay quiet out of embarrassment and, as a result, can hear low moans from next door as the woman gets more into it, undoubtedly turned on by Avery's escalation.

Soon Leigh can no longer hold back her own noises. She continues to be able to hear the other woman as she grows louder, as if their neighbor is trying to be heard. Soon all three women are a cacophony of sex noises filling the bathroom, and all three cum in quick succession.