I've personally never experienced that happening, but I've heard from a few other soapers that having too much cleansing power from coconut oil in their recipe will cause a bit of irritation down in the nether regions. Does it burn any other part of your body? If so, it's possible your soap could be lye-heavy. Have you checked for zap?
I took a look at your recipe on SoapCalc and it has a pretty high % of cleansing action going for it, with a fairly low amount of conditioning in comparison. Everyone's skin is different and some might be perfectly happy with that much cleansing power, but it looks to be too cleansing for my own likes.
This is just me, but if I were to make such a soap, I think I would want to superfat it by at least 10%.
Also- Daryl brings up a good point about peppermint. That'll do it, too. My hubby tried one of my peppermint soaps once, and once was enough. He calls it my 'evil soap'. Nuff said.