There is supposedly this guy who likes me. However, when he is around me, he totally blows me off! Why do guys do this? Since this isn’t the first time this has happened to me, i’m kinda wondering why guys do this.
making no claims to know if this guy actually likes you or not, I can offer two insights from one guy…
legal disclaimer, I am not all guys, I do not speak for all guys, in fact I’m not even a normal guy, so don’t quote me on anything… and my name isn’t even bobo…
I personally have made comments in ‘confidence’ to other guys or female friends that I find <insert female here> attractive… and through the rumor mill this attraction became common knowledge, whereas I did not know that it was common knowledge. so on next seeing this girl, I would not openly show my desires/feelings/wants/longings/lusts because I assumed that no one else knew, and I didn’t want to make an ass of myself… so I would just treat the girl in question as anyone else and show no specific interest… I don’t know if that counts as ‘blowing her off’, but since I didn’t fawn over my other friends, I guess I always sort of blew them off too…
possibility the second… if you know that he’s interested, and he knows that you know… he might simply not be forcing the issue… maybe he’s seeing if you react favorably to his thoughts/desires/etc… once again, no need to make an ass of yourself if it’s not going to go anywhere…
just the insights of young married man… 
He may be so attracted to you that he feels that if he does or says anything around you, he’ll make a fool of himself. At least that’s my guess.
done that one too…
and for all you lit-buffs out there… I know that’s probably not a perfect quote… so bite me…
Fear.
Boyz are stoopid.
Men are told again and again that women are attracted to “extreme self-confidence”. Maybe he is trying to exhibit that by acting overly nonchalant around you.
If he’s a player, his aloofness is a ploy to get you thinking about him more often than if he actually paid you any attention.
If he’s a player, he’s got you unsure of yourself. You’re thinking, “Why is he acting this way – I thought he liked me!” “Does he really like me?” “Why doesn’t he like me?” “What can I do to get him to like me more?” “Maybe I can find the answers on the Straight Dope Message Boards.”
Etc.
He’s just after your drawers.
Soon, he will notice you. He separate you from your friends and compliment you shamelessly. The words, “You’re different,” will come up. You will believe him. He will give you lots of attention, have a brief but passionate, intense fling involving some form of oral gratification. He will then ignore you pointedly, especially around his friends.
Your anxiety about him will increase at LEAST tenfold. You will feel you’re not good enough for him. That’s the point.
He will ask you out again. Somewhere private. Somewhere at night. You will rise to the occassion by pampering yourself into the best looking almost-professional supermodel in your price range. He will not really care.
He’s just after your drawers.
You will be giving up the drawers by… hmmm… 10:27 pm at the very latest. Assuming he actually did have some place to show you off first… posiibly an old girlfriend, so he can get her jealous enough to agree to have sex with him later.
It’s all in the National Player’s Handbook, revised 1997. The Clinton Edition. What, they didn’t TEACH you about it in school??
Yeah, but only around the girls we like. Funny the way that works, isn’t it? 
WTF? It’s not available on Amazon or eBay? But I need it! Er, um, for class…
[sub]Okay, I’m going now.[/sub]
Because he doesn’t really like you. Turn to alcohol and drugs to dull the pain of your meaningless existence.
I’m not joking.
Has anyone else noticed that oldscratch seems a little bitter lately?
That’s . . . not much to work on.
Maybe he likes you so much he’s afraid of spooking you. Maybe he has poor social skills, and is unsure how to display affection, or doesn’t even realize that that’s expected of him. Maybe he’s playing cool, hoping you’ll find that attractive. Maybe he doesn’t like you as much as you think, and is trying not to hurt your feelings by actually rejecting you. Maybe he’s too shy to display affection in front of other people. Maybe he’s involved in a vast machiavellian scheme to confuse you, use your body and discard you. Maybe he’s wondering why you’re not being more affectionate to HIM. Maybe he just bought Fallout 2 and is trying to figure out where the hell Vault 13 is hidden, and doesn’t realize how he’s coming off.
Maybe you should talk to him about it.
The more important question is probably, how do you feel about him?
–
“Familiar, Mike? Women dumping you for ventriloquists?”
Youch…, oldscratch. That’s certainly one scenario, but it’s one of the harshest out there.
Be that as it may, the other situation that might be going on is that he has low self-esteem and is (and this is not a conscious action by any means) acting like a jerk to test the waters. The theory being “if I treat her like scum, and she still likes me, than I must be something pretty special”. This would most likely be a consistent theme in a relationship with someone suffering from this issue, so I would make sure that he doesn’t seem passive aggressive to other issues/relationships.
Just a thought.
Also, I agree with the other posters that it is likely that he doesn’t know that you know, and he isn’t going to show his interest (too easy to get shot down) until there is sufficient evidence that you will respond favorably. And, if you are expecting him to show interest and he is acting no different to you than he is to other friends, then you might be interpreting that as being “blown-off” when it is only that your perspective has changed.
Good luck figuring it all out!
I agree that it could be any of the above possibilities: fear on his part, swaggering over-self-confidence, plain ol’ guy-like stupidity, excessive horniness, etc., even oldscratch’s admitedly harsh answer. We men are difficult to figger our sometimes.
But, having said that, I would like to point out that, um, women do this too. Unless I’m the only guy this has ever happened to in reverse? Am I? Hello?
You must start collecting cat figurines and bring them to school. After a while move on to real cats. When you have no more money to feed yourself and the cats, sell the cat’s for cigarettes and several boxes of cheap wine.
That wins them over every time.
Is there supposedly this guy who likes you or this guy supposedly likes you?
Don’t you think that if this guy liked you he wouldn’t blow you off?