It means he is creepy. Most guys check out girls, but they tend to look away if they get caught out because it's kinda awkward...
If I guy doesn't stop staring they are either a perv or a weirdo so you're probably best staying away from him.
Who knows what kinda sick thoughts are running through his head as he stares at you, undressing you with his eyes... Like I said: CREEPY!!!
If he genuinely finds you attractive and wants to look at you, then why isn't he coming up to you and talking? He's obviously not shy because he doesn't mind standing there gawking.
