From the last thread:

Sirma goes about her daily gym routine as usual and then a group of new girls with big asses take a liking to her and befriend her. This goes on for a while until one day they get her to hang out with them and she winds up drugged by the girls and used as a foot cleaner, human toilet and ash tray in the ladies bathroom for not only themselves but all women that come by. Even after the party they repeat this every week since sirma cannot escape from them out of fear and bondage