A Story in the Old Fiction Files

[Arab Nights (imported)]

Wifey and I were in a hot tub over the weekend. It reminded me of a story I had read in the past. I tried unsuccessfully to find it. I think it started where a guy somehow helps a neighbor woman get a pool or hot tub set up. She invited him to swim as a reward. Somehow his wife gets involved. So there are the two women and the guy. The women eventually show that their tits float and challenge him to show if a dick and balls float. Somehow that leads them to talk him into castration.

If this at all approaches a real story and anybody knows the author or title so I can look it up if it is available, I would appreciate it.