Sadly, stories like Jeb's are becoming all too familiar. In a few short years, Facebook has leaked out of the college dormitory like some rare tropical disease and has begun infecting grown men in disturbingly vast numbers. The fastest-growing demographic among Facebook's 64 million users is those over 25. More than half of MySpace's 110 million users are older than 35. The hosts, once infected, exhibit a tendency to "superpoke" each other, hyperventilate over friend counts, and share their thoughts about the latest episode of The Hills with hundreds of near strangers—behavior normally associated with teenage girls, not men in the middle of their fourth decade. Somewhere tonight, a man with a successful white-collar career and a family who needs his attention will log on to his MacBook to see who "trout-slapped" him and left him a "zombie hug"—hypnotized by the soft glow of the LCD screen into thinking his online popularity has some kind of bearing on his life.

"I'd say 90 percent of my friends have that silly page, putting 'funny' pictures of themselves half-naked and drunk on them," says Michael Lupo, 26, a marketing director in Manhattan who says he's never given in to their pleas to join them. "There are so many bad attempts at being quasi-famous. These people who have like 10,000 friends? I'm like, 'But they're not your friends—you do realize that. You don't hang out, and you don't know anything about them besides what's on their Facebook page.'"

Sure, it's difficult to resist the allure of a site that everyone with Internet access seems to have embraced with open arms. But that appeal might be worth scrutinizing if the same site causes otherwise judicious adult-male converts to behave like 13-year-old girls.

"There's a sense that you're actually accomplishing something when you're on these sites," says Dr. Jerald Block, an Oregon psychologist who studies Internet addiction. But the truth is, other than the adolescent joys of Scrabulous and Alias trivia, there aren't too many benefits to this site that can't be realized via e-mail and telephone. Take a good, long look at your friend list and ask yourself how many of these people would meet you for a beer—or how many you would actually want to meet for a beer. And did you really want to reconnect with that awkward kid from boarding school who drew battle-axes on his Trapper Keeper?

Of course not, but once you decide to join Facebook don't be surprised if you're no longer in control of your self-image. For Michael, a 24-year-old private-equity associate in Chicago who decided to delete his profile, the promise of social status just wasn't enough for him to make that kind of sacrifice.

"You really don't get to control your own identity on the site," he says. "Other people can put pictures of you up there, tag them, write on your 'wall'—and all of a sudden you've got the one 'hilarious' buddy from high school to deal with, who you love but who maybe doesn't realize that you've got colleagues looking at your profile."