One who is incapable of chatting up girls in real life and therefore resorts to stalking them online.
So let's say this kid stumbles across a girl's youtube account where she posts occasional vlogs - he finds her physically attractive. He will then google (and perhaps even yahoo) her username and see if she's signed up to any other sites with that same name. Let's say he finds something (Friendster, myspace), he will then try find any information about her he can. This could include where she lives, her age, interests, whatever. If there are any pictures of her on one of these sites he might even save them to his computer (provided the given site allows it). Then when he's gathered what he believes to be enough information, he'll contact her somehow and surprise her by pretending that his interests or whatever are congruent with hers. Say she's from Philadelphia - he'll put on some bullshit about how his Grandparents grew up there. And so on and so forth - that is an internet creep.