The guy who seems to be in every movie, every TV show, but you still don't know his name.

Refers to Call of Duty: Modern Warfare 2. In every game you build up a killstreak, that eventually gets shot down by some jackweed. This jackweed is known as "That Guy", or someone who spends the whole game shooting peoples hopes, dreams, and AC-130's down.

That Guy is the baddest motherfucker on this earth, you can usually hear about him in tv shows when the main characters are jealous because "That Guy's getting laid by those two gals tonight" or "That Guy actually bought Playboy Mansion".

An easy mistake to make is hear about "that guy" and believe people are referring to "That Guy". The two are polar opposites, one being the pinnacle of awesome and the other being a retarded pussy that frequent parties orchestrated by 15 year olds.

While That Guy is pretty cool, he's also an elitist asshole, so you're probably not his friend unless you're easy and pretty hot, in which case you're not reading this.

"That Guy" is the guy that you know of, but do not know personally. You see him at the bowling alley every week and he is just the sliest old man you've ever met. That guy has bowled 300's on several occasion which makes you want to know him even more. He's an asshole and as much as you want to hate him you cant, because he's THAT GUY. Just when you think you've had enough of THAT GUY, he openly makes fun of a person you dislike and he draws you in even further.

(N.)(that-guy)The guy who drives at night with those blue lights on his car AND his high beams on, but ONLY uses them when it's a perfectly clear night, and he shines them right into your bedroom just to wake you up before work. He does this multiple times a night just to make sure you don't go back to sleep.
He also drives behind people to make sure they can't see SHIT.

Someone who's always calling a girl, or IM-ing her, or running into her at a bar. He always flirts with her -- and even thinks he has a shot -- even though she's made it perfectly clear that she's not interested. Not as malicious as a stalker, just annoying.

A person who constantly ruins jokes by repeating them, especially inside jokes that they were not a part of. He also is annoying and made fun of behind his back by all his friends. He tries to do stuff outside of the box, but wants to make sure everyone knows he is doing it by informing them in great unnecessary detail that is not needed and laughs half of the time he is explaining his dumb ideas. He sometimes may also score the hottest girl at your school some how and no one knows why. He may also try to join groups of friends uninvited.