Trying to lay down a pat definition of what is sexy is no easy task, from the perspective of either gender. Interestingly when I checked with some female friends and colleagues on this matter—asking what they found sexy in guys—the response was almost invariably "total self-confidence."

This is apparently not to be confused with arrogance or egotism, but it surprises me that so many women have the same opinion of what they find sexy.

It also surprised me that it’s so intangible. Men, on the other hand, tend to judge sexiness primarily by more quantifiable criteria. This doesn’t necessarily mean that men are shallow beasts; after all, if you see someone at a party and have to make a quick judgment about them from across the room, it’s easier to think "pretty eyes" than it is to think "remarkably confident."

It could just be a matter of efficiency. I certainly don’t think many men find a lack of self-confidence or brains very sexy; it’s just not their chief measurement. It may not be the first thing they look at simply because it’s easier to see those subjectively sexy physical attributes.

Subjectivity is the key.
For every pig out there who would shout "nice rack," you probably can find ten more guys who would say, "nice blonde girl" instead. Men simply tend to judge potential partners based on appearance at first, but that’s not necessarily how they are throughout the entirety of a relationship. Once a guy gets to know someone he finds sexy at the outset, it’s her inner qualities that will make her even sexier. And you have to agree it’s more efficient, even if it is somewhat dismissive.

The reason that there is no specific definition of sexy, down to colors and measurements in the millimeters, is that the world is full of people, and a lot of them would be out of luck if they didn’t match the standard. Fortunately what sexy is can’t be quantified from person to person. Oh, there are some that almost all of us agree on. Get together with your friends and make Top Five lists. If none of you can agree on anything, at least you can be sure that you’ll never fight over women.