1. Use It or Lose It
You need to have erections regularly to keep your penis in shape. "It has to be essentially exercised," says Tobias Kohler, MD, assistant professor of urology at Southern Illinois University School of Medicine.
2. Your Penis May Be a 'Grower' or a 'Show-er'
Among men, there is no consistent relationship between the size of the flaccid penis and its full erect length.
3. The Pleasure Zone
Many men consider the underside of the glans (head) of the penis and the underside of the shaft to be most sensitive to sexual pleasure. Researchers asked 81 healthy men to rate the erotic sensitivity of different areas of their bodies, including not only the penis but also zones such as the scrotum, anus, nipples, and neck.
The underside of the glans and underside of the shaft had the highest sensitivity rating for a significant majority of men, followed by the upper side of the glans, left and right sides of the glans, sides of the penis, upper side of the shaft, and foreskin (for the minority of men who were uncircumcised). The study findings were reported in the British Journal of Urology International in 2009.
4. Sensitivity Declines With Age
Studies show that the penis steadily loses sensitivity as men age though it's hard to say exactly by how much.
5. Vibrators Work on the Penis Too
Vibrators aren't only for women. They work on the penis, too.
6. There's More to the Penis Than Meets the Eye
"Most guys would be proud to know that their penis is twice as long as they think it is," Kohler says.
7. Your Penis Is a Habitat
The skin of your penis is home to a diverse community of bacteria.
8. Most Men Aren't Circumcised
Worldwide, approximately 30% of males aged 15 and older are circumcised, according to a 2007 report from the World Health Organization (WHO) and UNAIDS.