Chlamydia (clam-ID-ee-ya) is the most common STD in men (and women). There are over a million cases of Chlamydia in the United States, with men accounting for over 250,000 of these. (Do the math, ladies.)

How soon before symptoms? Between five to 10 days following the interlude.

What to look for: Chlamydia infection in men often goes undetected because it frequently causes no symptoms (which may be why it's the most common STD). When it does cause symptoms, pain during urination is the key finding. It can also cause a watery discharge reminiscent of a leaky faucet. For those engaging in anal sex, Chlamydia offers anal discharge and pain with pooping.

Can I get rid of it? Yes, with some chicken soup from your favorite restaurant and, more importantly, antibiotics from your favorite health-care provider.