Ferriss, who's become something of a cult figure since the publication of The 4-Hour Workweek, his best-selling self-help book for terminal multitaskers, created a novelty T-shirt with the words I MAN CRUSH YOU on it after that Valentine's Day epiphany. (He sells the shirts on his website.) The point of the tee, he says, is to help guys show their friends that they "love them, but in a Platoon way, not a Brokeback way."

Homosexuality, of course, used to be known as the love that dare not speak its name—until, thanks to the gayification of pop culture, it became the love that wouldn't shut the hell up. Now the man crush (a heterosexual male's feelings of platonic love for another man) and the bromance (when those feelings are reciprocated) are coming out of the closet in a major way. This has been brewing for a while (remember those "I love you, man" Bud Light commercials?), but it reached a high point in the already-classic drunken exchange in last year's Superbad (which also coined bromance), in which Seth tells his buddy, "I just love you. I just wanna go to the rooftops and scream, 'I love my best friend, Evan!'"

The fact that some guys now not only admit to same-sex infatuations without suffering a paralyzing identity crisis but announce them amounts to a seismic cultural shift. Until recently, if a heterosexual dude wanted to reveal something about his inner self, the safe (i.e., non-gay-seeming) option was to take a stand about, say, The Killer versus Hard Boiled. Now he can hold forth about his taste in men.

Tom Brady was a significant factor in the man crush becoming part of the lingua franca of male bonding. In the run-up to the Super Bowl this year, the square-jawed, Gisele Bündchen-dating quarterback became the go-to man crush for many American men, including viral-video auteur Dave Hoke, whose comic music video "Tom Brady Mancrush" scored more than 100,000 views (on YouTube and Funny or Die) within weeks of its release in January. Hoke traces his man-crush revelation to a Pats press conference after Game 13 last year: "Tom Brady comes out with a cardigan and a tie and jacket, and it's almost like he had his five o'clock shadow trimmed to be the perfect five o'clock shadow. And he had a pocket square. Like, who does that in this era? I turned to my wife and was like, 'You know, listen, I'm not gay. But if I was, this guy would be the guy.'"

Women have long been vocal about girlfriends and celebrity females they think are gorgeous or adorable, but many guys haven't yet arrived at the same point as Ferriss and his Valentine's Day date; they need the relative remove of celebrity to declare a man crush. That's the idea behind mancrush.com, a site that lets its male users vote on the relative crushworthiness of famous dudes living and dead. Eric Vecchione, its founder, got the idea for the site in 2005, during his senior year in college, when he realized that discussing man crushes had become a way for his buddies to relate to one another: "We would be watching a game or a movie . . . and the debates would start: 'Are you man-crushing on Johnny Depp?' Or 'I can't believe you have a man crush on Derek Jeter!'"

According to Geoffrey Greif, a professor at the University of Maryland School of Social Work and the author of an upcoming book about male bonding called The Buddy System, the rise of the man crush may be bringing guy culture full circle. "The word homosexual didn't even exist until the late 1880s or 1890s," he says. Greif adds that once upon a time, expressing same-sex admiration was the norm among red-blooded frontiersmen who didn't have the conceptual framework to fear that they might be labeled homos. "A lot of the founders of our nation would write letters to their male friends saying 'I can't wait to see you again. I love you; I can't wait to get together with you,'" he says. "Somewhere over the last 125 years, it became no longer okay for a man to present himself that way."

That's the beauty of a modern-day man-crush declaration: It gives a guy a sort of wry shorthand, allowing him to say something meaningful about his masculine ideals without having to actually spell them out. As Ferriss notes, "Male vocabulary is limited when it comes to expressing positive feelings about other men. We've got like three adjectives: cool, awesome, badass. I'll give you an example: There's a guy named Dave Camarillo. He's a professional Ultimate Fighting Championship grappling trainer, and he's also my jujitsu coach. The guy's a total stud. I mean, he's one of the top trainers and jujitsu and judo practitioners on the planet, so the guy's a total badass." He laughs, then adds, "So I have a serious man crush on him, yeah—in the purest heterosexual way possible."