This topic reminds me a bit of the
snooping topic, but slightly different.
with snooping you intentionally "snoop" around, through underwear drawers, on computes, phones... but this is different.
So, here is my "you shouldn't have" experience, although I also posted a few in the snooping topic.
My sister repeatedly asked if I could transfer her Hi8 tapes to DVD (when DVD was still popular, quite a few years ago). Mostly from their wedding, their first kids, some vacations, and such. I finally made time for that, and transfered 7 or 8 tapes to my computer. I used some software to create DVD menus, with chapters, moving thumbails, text and so on.
It seemed the moving thumbnails on the DVD menu were random clips of a the specific video. So, before burning them onto DVD, I checked if it all looked good. And to my shocking surprise I saw my sister fully NUDE in one of the "thumbnails" of one video!!!
My heart was beating so very fast. I immediately clicked the thumbnail, and saw this 2-3 minute video was of her being in the shower, playfully cupping her breasts, giving a few "seductive" smile to my brother-in-law, AKA the cameraman.
Obviously I changed the menu/thumbnail into something more innocent, before burning it all to DVD. After I handed her the DVD's, I still took time to check out the source files on my computer.
I watched for hours and hours, but all the "naughty" stuff was those few minutes of her in the shower. Oh well, it was still hot to see!