In 1991, Duke University funded a study to see why the head of man's penis was larger than the shaft. After one year and $180,000, they concluded that reason the head was larger than the shaft was to give the man more pleasure during sex.
After Duke published the study, Stanford decided to do their own study. After three years of research and $250,000, they concluded that the reason was to give the woman more pleasure during sex.
The University of Alabama, unsatisfied with these findings, spent $13.27 (for a Playboy, Penthouse, and case of Old Milwaukee) and concluded it was to keep a man's hand from flying off and hitting him in the forehead. :-D