You're at the urinal when something catches your eye. Something alarming. You hold your breath and take a long, long look--paralyzed. There's a bump. Down there. Not a big bump, but one that you know wasn't there before. You look away, and then you look back--in fear--hoping you didn't see what you thought you saw.

But no, the bump actually looks bigger now. You touch it. Is it a pimple? An ingrown hair? An allergic reaction to soap? "Oh God, please--not this!" Your mental sex calculator goes wild. The Tuesday quickie with the neighbor? But that was just a second, and you didn't sleep together. Last month with the hottie from work? But she'd just gotten out of a long-term relationship. After happy hour with the flirty redhead? Yeah, but she looked so . . . pure.

It doesn't matter how it happened. Whatever topical ointment you apply, and to whichever patron saint you pray (swearing you'll never let Jimmy out to play again), the bottom line is you're now a member of Club Herpes, where you can check in but never check out.

According to the American Social Health Association, at least one of every four Americans will contract an STD (other than HIV) at some point in their lives--more people than at any other time in the past. How bad is the problem? The Centers for Disease Control and Prevention has gone so far as to label the spread of STDs an epidemic. U.S. gonorrhea rates are the highest in the industrial world, up nearly 10% in the last decade, after a 72% drop between 1975 and 1997. And after hitting an all-time low in 2000, syphilis rates are also on the rise for the second consecutive year.

Perhaps most shocking of all, in the era of safer sex, is how herpes infections have increased by more than 30% since the '70s. At the same time, a startling one in three college-age women are infected with the human papilloma virus (HPV), while the National Institutes of Health estimates that 60 million Americans have genital herpes, and another 500,000 people will become infected each year (80% of those aren't even aware of it). And then there's chlamydia, the most widespread of all STDs in the U.S. Chlamydia rates have soared by 37% in the past five years.

Do the numbers lie?
Many men suspect that STD rates are exaggerated--inflated by government agencies clawing for research dollars. But Toby Anderson, a social worker in Manhattan, knows otherwise. She handles STD test results on a daily basis. "Sure, the stats are higher than what we know," she says. "Those are only the documented numbers. Real statistics for diseases with a stigma attached to them, like STDs, are far higher than what have been published. What's frightening to me is the exponential rate at which they are rising."

Anderson is right to worry. Consider: A 2002 report in the journal Sexually Transmitted Diseases says that nearly 50% of all women and 40% of men could suffer from genital herpes by the year 2025. For those of you not so good at math, that means half the chicks you know. And the projected transmission rates for other STDs are equally alarming.

What's behind the spread?
Unsafe sex is the biggest factor. In a 2004 report, the American Journal of Health Behavior revealed that many men would rather catch an STD and have it treated than deal with the "hassle" of condoms. And even condom users are having more sex than ever before, and doing it at a younger age--increasing their total number of partners and their STD risk.

Research conducted by the CDC show that 65% of high schoolers have had sex by 12th grade, and 20% have had more than four partners. People are also getting married later, which allows them to have more partners.

But perhaps the most significant factor is that many of the infected have no symptoms, so they're passing infections on and don't even know it.

The good news? (Yes, there is some.) Most STDs are manageable if caught and treated in time. Some, like gonorrhea and chlamydia, can be cured, while others, like genital warts, can be treated--though you'll live with the virus forever.

That's why for many men, dealing with the ramifications of an STD can be just as difficult as getting past the condition itself. "For those who get a clean bill of health, getting tested can be a terrific relief," says Lorna Myers, a New York psychologist. "For those who don't, there is an enormous sense of shame."

Frank Montalvo, 28, heard the news that he had gonorrhea last year. "I was totally caught off guard. I didn't expect it at all," he recalls. "I got lucky--my girlfriend didn't flip out. Her best friend had already had it, so she'd read up. I felt so grossed out. It was a relief that I just had to take antibiotics for a few days."

How to stay safe
First, skip the vows of celibacy. You don't need to be a monk to avoid STDs. Instead, visit the doctor and get checked out and, if necessary, treated. Remember, doctors do this stuff all day, so while the visit is embarrassing to you, for them it's just business as usual. "The whole procedure is usually pretty simple," says Jack Bruder, M.D., a urologist at St. Vincent's Hospital in Manhattan. "Depending on the patient, it takes about 20 minutes."

The key areas to cover? Make sure you get a blood and urine screening, along with a complete physical exam. (In doctor lingo, that's a complete urinalysis along with a comprehensive metabolic panel and an STD panel.) Avoid peeing for at least two hours beforehand and the doc won't even have to whip out those scary swabs you've heard so much about.

And that's it. A couple of questions about your rig, a quick analysis of your family history, and then you urinate into a cup and give some blood. No painful prodding, no testicular torture, no nurses asking humiliating questions. If everything checks out--and you continue to keep things safe (note to self: cancel trip to Thailand with frat brothers)--you could be the only guy on your block without an STD. Then the only thing you have to sweat is staying that way.