The feeling of itchyness that occurs from having pubic hair grow back a little while after you shave. It usually only lasts for a short while, until the hair grows more fully or the person shaves again. When the person shaves again, however, cactus crotch is sure to come back temporarily.
I am always itching my private regions whenever I get cactus crotch. I generally get funny looks in public when I do so, and I like to wear sweatpants when I have the infirmity.