Actually this a valid scientific question. Consider the many environment variables involved here: humidity; ambient temperature; restrictive underwear (or otherwise); absorption powers of said underwear and let's not forget the indigenous flora and fauna. I'd take swabs for microbiological testing, 'cuttings' from the pubic hair and skin scrapings for microscopical examination. Then again, he could just have a girlfriend who is free and easy with her sexual favours. We'll await further enlightenment and the lab tests.