If someone came up to you and asked, "Hey, wanna make out?" unless you were a little cuckoo in the cabeza, more than likely you'd look at him funny and back away. Men might like it, though, because at least you'd be unambiguous.

In the journal Personality and Individual Differences [1], researchers asked 40 women between 19 and 22 what kinds of opening lines they might use to tell men they're interested in dating them. Although women get mixed messages from magazines and advice columns on the subject of whether or not men like being asked out by women, the men in this survey said they preferred a direct woman [2]. Want to know why? Then,

One of the main reasons? Although women think they're sending clear signals that they like someone, it's been shown that they often behave no differently toward a man they're not interested in than one they are — at least for the first minute or so of an interaction. (Perhaps because we're taught to be nice and polite, no matter what?) In the fourth and 10th minute, though . . . that's when the signals are less ambiguous.

I don't know about you — but I try to be friendly to everyone, so I could see how a man I'm not interested in might think I am, but for the one I am interested in? Short of asking, "Wanna make out?" I'm a big enough flirt that he'll know for sure. How do you let someone know that you're interested in him?

Source [3]