A relative of mine had a beshow (in the 70s) without even realizing she was on a beshow.
She was in seminary in Israel (uncommon at the time) and was invited to a Yerushalmy relative for שבת. They decided that it was their responsibility to marry her off and step in as surrogate parents (who were in America, and had no idea).
So, in middle of the שבת day סעודה, the downstairs neighbors, a chasidishe bucher and his parents come in and join them at the meal. They are all shmoozing for a while (she doesn't think anything of it because in her american community, family friends is a normal thing). The two couples withdraw into the kitchen, and she is still shmoozing with the bucher. Eventually, he asks her if she wants to go onto the mirpeset, and they shmooz for a bit there. (she still doesn't think anything of it, because, again even among the frum in America then, it wasn't taboo) The family leaves and they continue the rest of shabbos as if nothing happened.
Motzai Shabbos, right after havdala, there's a knock on the door. It's the family from downstairs. And they want to sign the tenaim. She's so terrified that she grabs her bag and runs all the way back to the seminary dorm (in a neighborhood that's pretty far) collapses into her bed and cries into her pillow.
