A boy likes me but I don't like him back and he's gonna ask me out to my face?!?

If he says anything, or asks again just tell him you like the fact that he has the guts to be up front, but that you just dont see him that way. The simple truth is much easier than anything else, and while it may hurt his feelings a little, he will respect you more for being honest with him. If he does not say anything, then let it go.