When a guy....

When a guy say he likes u ..wht u think u should reply bakkk?????

"I'm fifteen. I have more interest in school than in boys."

Seriously, it's up to the person being told and whether they have feelings for the person telling them. If you don't but are friends then just say that you would like to stay friends.

What you honestly feel for that person. DUH.

I would (if I liked them too) smile and look away then cutely say "I like you too _____. A lot." And smile again. lol
If I didn't then I'd blink a few times, look away, look back, and say "I dont want to hurt your feelings but I dont like you like that....." and then I'd act like it was nothing. Just so that they felt okay afterwards.... If I didnt know them, I'd roll my eyes and walk away. lol I'm mean!

This question is too general. It really does depend on the circumstances.
But I agree with Mindy:
"What you honestly feel for that person."
^yeah.

I agree as well

Simple, they've told you they like you so you have to give them an hinest reply. If you like the guy tell him so if not then dont be too harsh but make it clear to him that your not interested