IF HE'S SHY, when he's with his friends, he will turn around to see what are you doing, smile at you when you look at him. He might ask stupid stuff, try to get closer to you, talk to your friends. If he's afraid to talk to you and look at you in the eyes when you ask him a question, he may just be a shy guy. If he's not shy, he will let you know.
http://www.wikihow.com/Know-if-a-Guy-Likes-You
happens allthe time
Ask him!
asking him would work
get to know him then he won't be shy
it might be he wants to know if you like someone or you might have a crush on him
He'll look at you differently.
if he is still shy to me
From what i Understand of "De-crush". If you want to decrush a guy, when he has a crush on you then you should tell him as soon as possible. You should let him know that you know he has a crush on you, and that right now you are not interested but can be friends etc. The more time you leave it, the more painful the result will be. If however you meant that you have a crush on a guy and you want to stop it, then simply put it aside and think of something else. lol
Its because they know about your crush
if he is being mean or hurtful towards you (usually)
Crush him back..