Anyone know any conditioning stories?

So I'm specifically thinking about a story I read years ago (not on Reddit, but it could be on Reddit IDK) where a sadistic sister conditioned her brother to associate a common sound with testicle agony so that any time he heard the sound, even though his balls aren't physically getting hit they feel like they are. For example (not exactly what happened) she "conditioned" his brain to associate the ding of the microwave with a full force kick in the nuts, by kicking him every time she used the microwave that way any time he heard a microwave he'd feel agony.
I'd love to read that story again but if you know any story similar to that I'd love to read it as well.