It's a concept called "I'd do her"**. It's usually said that way, and often offered with a shrug.
The gist of the concept is that men will consciously categorize any woman into one of two categories based solely on physical attributes that they deem desirable. It is my contention that men do this on at-least a sub-conscious level immediately upon seeing any woman for the first time, but that's a lot harder to prove. It has nothing to do with personality. It has nothing to do with feelings. It has nothing to do with present circumstances. It's a blue-sky, fantasy-world of carnal desire that is hard-wired into the male psyche. It's the difference between specific attraction and general attraction. It means that, if given an ideal set of circumstances as it applies to the individual's inner ethics and morality, that they would "do her". Maybe it'd have to be in wedded bliss, maybe it could only be a hook-up because the thought of her personality is so distasteful. You can argue all you want about where it originates, nature or nurture, but the fact remains that it exists.
This may seem terribly obvious. Of course if everything was sky-blue fantasy: if I didn't think she was annoying, if I wasn't married, if I... you can go on forever. But my point is that Guys have cut
"I'd do her".
To make it a little easier, here are come basic scenarios:
Scenario 1: Guy One mentions his attraction for HOT CELEBRITY. Guy Two makes a face and says he never thought she was that attractive. Guy One challenges Guy Two with "You wouldn't do her?" It now has nothing to do with specific attraction but general attraction. Chances are that HOT CELEBRITY isn't morbidly obese or severely disfigured, so the honest answer will almost always be yes. A variation on this scenario is that Guy Two doesn't "like" HOT CELEBRITY for whatever reason (undesirable public persona, dislike of her entertainment value, lack-of entertainment value, etc.) but when challenged would have to admit he would indeed do her. This is the way that most guys feel about your musical-pop-tart flavor-of-the-month-diva at the height of their hype. Another variation of this scenario has an era delimiter ("I'd do 60's-era Eartha Kitt").
Scenario 2: Two guys are having lunch at a food court in a mall. To fill the silence between them, they play a casual game of "I'd do her" directed at anonymous ladies passing-by. There are variations of this game, but it's the same basic concept.
Scenario 3: A guy's girlfriend has an attractive mother/sister/daughter. This stands to reason since the guy is attracted to his girlfriend, but not universal. Obviously the ages of mothers and daughters weighs heavily into this. Under the rule of "I'd do her", he'd have to admit to it. Ladies, don't ask your guys this question unless you truly understand this concept and can handle what you'll hear. This is assuming of course that he doesn't lie to you, which he probably will.
o where's the question in this? I'm glad you asked. While I don't think it's universal, I'm sure it's very, very common. So guys, I want you to think of work (or school). It's a place there are likely females you see on a daily basis and have had lots of time to consider.
My question is, do you already have a mental inventory of who you would or would not do? As a side question: is there a hierarchy? In the blue-sky fantasy you could only "do" one, only once, and never any of the others, ever. Do you already know who it would be without thinking?
*This is not to to say that it is a purely Guy concept. I've known many females who do the same thing.
**This is not intended to exclude those of homo/bi sexual persuasion and I presume it is also applicaple with the third-person pronoun of your choosing.