I've tried multiple times to write a story with two celebs, one of them having a personal trainer she has sex with regularly. This celeb was usually Vanessa Hudgens since she strikes me as someone who is very much into working out. That other celeb is a friend of hers who wants to see what all the noise concerning the personal trainer is about, who was Hailee Steinfeld in my draft. They meet up in the gym parking garage to jump on the bikes he brought with his van in order to go cycling around the bike path in a nearby park, and both girls have been told to wear their usual work-out gear, but opt for tennis skirts rather than gym shorts.
The trainer reveals the bikes to them, his is normal, but both bikes for the girls have a dildo attached to the saddle, in a way that prevents them from just taking them off, maybe screwed on or something. This is where there would be some external threat of them being discovered, maybe someone coming, so the girls slide their panties down their legs and sit down on the dildos, hiding them this way. Vanessa would be used to the quirks of her trainer and be more into it, and Hailee would be deeply flushed, embarrassed and constantly chewing her lip. And then they go on their tour around the park, each bump in the path making them gasp and whimper. Perhaps with some hold-the-moan orgasms where the girls have to hold on to a traffic sign with both hands to remain in the seat of their bicycles.
I abandoned it because it started to feel somewhat silly once the dildos came into play, though I really like the public setting. Too much hinges on the gimmick. I don't know, maybe I'll pick it up again some day.