What does it mean when a guy looks at a girl with lust?

He's having some sick fantasies... lol. Yeah but if a guy keeps on looking at you constantly over a period of about a week. Then your chances are good. But if its a one time thing, he is very horny.

It means he likes you for sex, he wants that bad, but he would like to start a relationship. Look at his pupils if they are big he wants sex, if his feet are pointed toward you, and if his crotch is facing you he wants sex, if his feet are facing you and his pupils are small he wants a relationship, sex would just be a plus, if he looks at you and he fidgets with his hands, and pupils dilate, he wants a relationship, and not worried about sex.