Valentine's Day, of all things, for Timothy Ferriss to realize he had a man crush. "I was setting up a lunch with a friend of mine," says the 30-year-old entrepreneur, who lives in San Jose, California, "and he suggested that Thursday. I agreed, but then he wrote back, 'Oh, I completely forgot it was Valentine's Day—I don't know if you have plans to keep.' So I wrote back, 'Uh, well, that's why I asked you. You're my Valentine's date!'" Ferriss was joking with his friend; both are straight. "But then," he says, "it turned into this ha-ha, like, shoulder-punching exchange, where we were very awkwardly expressing that, yeah, we're cool dudes, we like each other—let's hang out. It was like a requited man crush."

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.'"