English has an idiom called peeping tom. It often comes up in fiction, especially in stories about cops and the like. It's a guy, probably a pervert, who spies on women. Seems clear enough, but when I heard it yet again I wondered: why Tom, and not Colin, Bob, or the traditional John?
It turns out the idiom goes all the way back to the 11th century and the legend of Lady Godiva. Lady Godiva was (really) the wife of Leofric, Earl of Mercia. And she was constantly fighting with her husband over the extremely high taxes he was strangling his poor subjects with. Maybe she felt sorry for the common folk, maybe she'd suffered from them herself, or maybe some respectable people asked her to. But Godiva kept begging her husband to cut the VAT rate.
All of that is pure historical truth. Then the legend begins. Once, during yet another debate, her husband says: I'll lower the taxes when you ride naked on horseback through the town of Coventry. And Godiva goes — deal! Basically, both were apparently hoping to call each other's bluff, but it didn't work out. Something had to be done. Notices were hastily posted all over town: today is a short working day, at the specified time everyone is to go home and wait for the Earl's address on TV. Close your windows, don't go outside, there's nothing to see anyway.
And then there was a tailor named Tom who said: what kind of cheating is this anyway, if everyone's hiding and nobody's watching, then it never happened. So I'm going to go and have a little look! And he went and had a look. Which is exactly why the other townsfolk called him a peeping tom.
Next, according to one version of the legend, Tom went blind. Either from the sight of Godiva on horseback in all her natural glory, or God punished him, or the Earl did, so that next time he wouldn't go against the collective. According to another version, there was no tailor at all. Some artist simply painted Leofric peeping at Godiva, and the common folk didn't know what the painting was about and made the rest up themselves.
But that's not so interesting anymore, since it's just a legend and most likely nothing of the sort happened. I mean, Mercia, Godiva and Leofric did exist. But there was no naked ride through Coventry and no tailor Tom. And yet the butt expression peeping tom does exist in English.