Sex, kinks, and respect (-)
@salameleon sounds like an awkward failure of the meme. Boundaries are appropriate to set but policing someone else's fantasies seems wrong. So what so you do when they have created a window to share them without context or scope, and so you get an honest view into something you'd rather not know about?
The prudent thing would have been a "sorry, it was something you aren't into", but then that sort of self-censorship is exactly what that thing isn't for.