Wearing Super-Skinny Hipser Jeans

Questionable dress and behavior choices can evoke ridicule from women, friends, and coworkers — but those calls may actually be harming your health. Why It’s Not So Cool: Leave the painted-on Levi’s on the rack unless you’re an indie rocker like Pete Wentz. The Health Risk: Doctors have noticed cases of meralgia paresthetica, or nerve-related numbness, in fans of skinny jeans. “The crotch (especially in men) and certain areas of the leg are sensitive to pressure,” says Mark Moyad, M.D., and codirector of the men’s health program at the University of Michigan. This goes for tighty-whities as well. If your current choice of underwear is so constricting you can’t feel your boys, for the love of God, try some boxers.

Covering Your Body in Tattoos
Why It’s Not So Cool: David Beckham can pull this off, but unless you, too, have a 12-pack, the saggy body as canvas is less than a work of art. The Health Risk: A British study reports that people with more than three tattoos generally suffered from low self-esteem. Of course, this isn’t a hard-and-fast rule. “Obtaining a tattoo, especially if it’s a rebellious decision, can be an exercise in control and reinforce the basic need for power and autonomy,” says New York City-based cognitive behavioral therapist Jayme Albin, Ph.D. Of course, you can always assert your control and win brownie points with a “I Heart Mom” tat — but you’ll be missing the rebel aspect entirely.

Looking Like George Hamilton
Why It’s Not So Cool: Two words — Jersey Shore. The Health Risk: See Spot. See Spot sun. See Spot’s liver spots. In a study from the University of Texas, only 14% of men covered all exposed areas of skin, while 69 percent of women did. “You should apply enough [sunscreen] to coat your sun-exposed areas evenly without leaving any residue,” said David J. Leffell, M.D., professor of dermatology and surgery at the Yale School of Medicine. And ditch the outdated trucker hat, too. “A cap does not protect the ears, and we see many skin cancers specifically on the top of the ears,” says Leffell. Just to be safe: Why not take a cocktail break (in the shade) from 10am to 4pm? You may not only avoid getting skin cancer but also save money on Botox in a few years.

Displaying Dirty Fingernails
Why It’s Not So Cool: Why bother hitting the gym and dressing for success when a speck of crud hiding under the tip of your pinkie screams “Mama never taught me how to wash myself!” The Health Risk: A British study showed that 24 percent of men harbor germs under their nails that could cause gastroenteritis. And experts say this is because the space under your nails is a prime breeding ground for a veritable cornucopia of viruses, including E. coli and salmonella. “It’s particularly a problem if you’re handling food,” said Charles Gerba, Ph.D., a microbiologist at the University of Arizona. Lucky for guys, short nails are easier to keep clean than the talons some ladies sport — and let’s just hope she’s washing well before making you a cheeseburger.

Obsessively Texting/Talking on a Cell Phone
Why It’s Not So Cool: We get it. You are super important and busy. But, if Obama can disconnect long enough to play some B-ball, maybe you can chill out for a bit? The Health Risk: Some researchers claim there’s a link between lowered semen quality (which included sperm count and motility, i.e., the ability to swim and succeed) and higher rates of cell-phone usage. “We found very high levels of free radicals in the semen samples that were exposed to cell-phone radiation says Ashok Agarwal, Ph.D., and the director of research at the Center for Reproductive Medicine at the Cleveland Clinic. His advice? Keep your cell phone in your shirt pocket and away from the family jewels.

Lighting Up or Chewing Tobacco
Why It’s Not So Cool: Anything that causes you to spit, hack, or show yellowing teeth in public isn’t going to help your image. The Health Risk: You’re kidding, right? Well, experts say that, in addition to the whole cancer thing, tobacco can damage and even kill your sperm. “The culprit is nicotine,” explains Ashok Argarwal. “Smoking excessively can result in a large number of white blood cells in semen. They are known to produce free radicals, which can result in damage to the sperm membranes and cell molecules.” There is hope — stop the habit and the damage can reverse itself, as sperm production is a continuous process. As is, coincidentally, the evolution of your personal style.