Today I heard some news about a Nigerian couple who got stuck while having inter/course. Such news aren't exactly uncommon in Nigeria, and the explanation we get for it is that the woman (who is most often an adulterer) has been laced with some weird form of black magic. This is untrue.
Apparently, the case of Peniis Captivus is not something unheard of in medical science. Wikipedia has an entry on it http://en.wikipedia.org/wiki/Penis_captivus
In addition, there have been reported cases of regular couples who are simply having normal, daily sex.
Peniis Captivus can happen if the woman develops vagi.nal spasms serious enough to entrap a man's peni/s. The good news, though, is that the chances of this happening is very, very small. Less than 1 in a trillion.

It would seem to me that Nigerians have some sort of concoction or a mix which is fed the woman, and which probably increases the incidence of spasms in her pelvic area. The many native doctors have probably had this formula for ages. This could explain how Nigerian men can successfully reproduce cases of Peniis Captivus. smh!