Friendly Fire

THE UPSIDE TO HAVING A "FRIEND WITH BENEFITS" It's quick and easy. You'll cut the mating dance in half. No plot, no story line—it's gonzo dating at its best. And cost-effective, too. No shelling out cash for dinners or movies and then only getting a peck on the cheek. Besides, you'd be hanging out with her watching SportsCenter, anyway. Why not get lucky afterward?

THE DOWNSIDE TO AN "FWB" RELATIONSHIP You send out mixed signals. It's a fine line to walk, according to Neil Strauss, author of Rules of the Game. "Most guys think that by vocalizing that they want sex yet want to remain friends, they might lose the girl," he says. "But if you're clear about what you're looking for, you have a better chance of pulling it off." She might end up wanting more. It's not her fault, she thought she could handle it. Then something bigger kicked in every time you had sex—the brain-bonding hormone, oxytocin. Move over kryptonite—this stuff is potent and makes her defy all logic. Now she wants to cuddle and finds even the most moronic of your traits endearing. Watch out! You may just have to chew your own leg off to get away.

HOW TO MAKE IT WORK Don't let her see you chatting up other babes. Even if you're just keeping things casual. According to Strauss, "You still have to give her the respect and not pick up other girls in front of her—that's just insulting." But do dig into her past relationships. Ask the girl about her track record beforehand, says relationship guru Pepper Schwartz, Ph.D. "You can learn a lot about a woman from her past behavior. Did she ever have friends she slept with in the past? Did it work?" If so, you might just get to have your friendship cake and eat it too.