For research scientists and applied epistemologists
 

In 1991, University of Maryland funded a study to see why the head of a man's
penis was larger than the shaft After one year and $180,000, they concluded that
the reason the head was larger than the shaft was to give the man more pleasure during sex.

After Maryland published the study, Princeton decided to do their own study
After $250,000 and 3 years of research, they concluded that the reason was
to give the woman more pleasure during sex.

University of Missouri, unsatisfied with these findings, spent $13.27
(for a Playboy, a Penthouse, and a case of Schaffer beer) and after one night concluded that
it was to keep a man's hand from flying off and hitting him in the forehead.