Three British educational institutions were commissioned by the
government to discover why the human penis is the shaped the way
it is.

Oxford University allocated a budget of $500,000 for research.
After 2 years they concluded that the reason the head of the
penis is wider than the shaft is that it fits better, when in
situ, so to speak. This would prevent leakage of semen and
increase the probability of successful fertilization.

Cambridge University spent $750,000 on a research program that
lasted 3 years. The results showed that the penis widened near
the tip because it maximized the number of nerve endings
stimulated during sex. This would lead to increased sensitivity
and a better chance of impregnation.

Finally, the Open University spent $2.50 on a copy of Playboy and
10 minutes in the staff toilet, only to discover that the penis
widens at the tip in order to prevent your hand from slipping off
the end.