Because he knows you have a crush on him, and you probably show it more than you realize.
You should go tell him that you like him
Of course not. There is not a 100% chance that your 'crush' even knows you
The world might end. No, but seriously why not just talk to the person? Who knows maybe they like you too.
Okay, I think I followed this; yes, if your crush's friend is asking you if you like your crush. YOUR CRUSH IS DESPERATE! otherwise he/she would probably try to keep cool and find out themself. I think this means your crush likes you.
Either to tease you, or because he secretly does like you.
Maybe your crush might like you back, but don't know what to say, or they might not like you and are avoiding you, or might be uncomfortable talking to you knowing you like them.
Most likely
act like your not bothered by it.
You send her a note that you like her and talk to her see if she go on a date with you
take her gently by the hand and ask her when your alone with her <3
You talk to your crush not making it obvious you like him/her if you do or if he/she knows. Just talk to them as if they are one of your friends and don't make things akward.......