Most of the time, the human body is an amazing machine that carries out a lot of unnoticed self-maintenance. We cruise through our daily lives, ignoring minor issues because they usually resolve on their own—a runny nose, a pulled muscle, a canker sore.

But for people with a penis, when something goes awry down there, we take notice.

Oh, you betcha we do.

And a lot can go wrong. Some penis conditions are common, some aren't, but even some of the common ones aren't well known. Test your knowledge of these five conditions.

Paraphimosis

In infants and toddlers, phimosis is a fairly common condition in which the foreskin on an uncircumcised penis is too tight to allow it to be pulled back over the glans, or penis head. At least 10 percent of uncircumcised boys will have phimosis up to age 3, though as the foreskin stretches over time and becomes more pliable, the condition becomes less