I remember reading an erotic story years ago and thought of you.
A woman had a program or app that would randomly send a pre-written message to a number from a contact list she made. The list had many men on it and she had no way of knowing who it would call nor any idea of who it called. She would set it to call a random contact and use self bondage with a time locking mechanism. She would be tied spreadeagle and the time lock secured her hands and would release her in several hours. She was also blindfolded, gagged, and she had plugged her ears. Soon a man would arrive and fuck her in any way he wished. Sometimes the man would bring a friend or friends. He or they would perform bdsm with nipple clamps, a clit clamp, paddles, flogger, post orgasm ......, basically anything they wanted. Sometimes it was just a quick fuck.
When finished with her he or they would leave and at the correct time the time lock would release her hands. She spent much of her time wondering who fucked her and how many men who were not on her list had fucked her. She also wondered if they took pictures and videos and if they did, would they or have they already posted them on websites she will never know about.