I remember trojan sponsoring a scientific measurement survey a few years back. The study was done by inviting random men ages 18-55 to measure just about everything on them trying to find corrolations between body shapes, sizes, ethnicity, and age demographics. I remember the results very clearly because you wouldn't believe how often these myths come up around friends and in casual conversations. I beleive the sample size was something like 1.5 million men around the country of the USA (making certain others note this). Many were invited to doctor offices, but most men were asked randomly outside of popular night clubs for a 15 minute measurement survey.
OF all body parts measured besides the penis, which include the head, arms, foot, toes, legs, hands, fingers, and nose, only ONE body part had a TINY corrolation of 11%. It was the left thumb. Everything else was 1.5% or lower in corrolation. So a guy with a big left thumb has a 11% likely chance to have an ABOVE average penis size. That's it.
For those wondering about other results...
The biggest "average" was held by white men at 150 millimeters (6 inches) that are between the ages of 21 and 25. Before that age 18-20, the average for a white male is around 148mm , and the size shrunk as the adult male aged over 25. This also corrolates to the average testostorone level found in males decreasing after age 25 continually until death.
The second largest ethnic demographic was african-americans at 147mm between the same age ranges.
The smallest average was asian males at 124mm.
Measurements were taken from fully erect males with a tape measure by measuring from the longest tip of the penis to the base without pressing down on the pubic mound of skin. The only demographics without a sizeable amount to include in the study were Pacific Islanders.
What was interesting to note was the flaccid states of measurements. Caucasian males on average were around 75mm when flaccid, asian males were around 72mm, and african-americans were 108mm when flaccid. Which is more often then not what promotes that african-americans are "hung" when infact they just look larger in the locker room but actually aren't.
There WERE extremes found in all races with penises over the 300mm for almost all races, and penises under 25mm when erect.
Other interesting correlations to note are that most men (57%) with larger flaccid states don't "grow" as much, hence the average size. Also, an overwhelming amount of men in the survey (92%) hung to the left. As in the penis tended to point more to the left side of the body then the right side or straight down the middle. Most men (95%) were bent at an angle, either right or left, with that remainder 5% having a perfectly straight rod. The other obvious note was that most men surveyed were circumcised (in america duh) so no relevant statistical data about men that were not cut could be taken. The last statistical inference, which means it wasn't a statistical note of this study but it is when compared to another, is that a study sponsored back in the 1960's with the same measurements, but a smaller sample size of around 500,000 men, found that the average "biggest" male was caucasians at 146mm. Which infers that the average penis size has been steadily increasing over the decades.
So for men, you can't judge a book by it's cover at all. You need to pull the shorts down and make him happy to get any real idea of what you are going to get.