OMG he likes me! What should I do?

I go to a church youth group and there is this guy there. He is sorta geeky... and he started to sit with me and my group of friends. He usually sits with the weird people. For some reason he only wants to sit by me.... And he does not shut up! I want to tell him to leave but I am afraid I will hurt his feelings... A couple of days ago one of my friends asked him if he liked me and he said yes! Now where ever I go he is right there! I can't get rid of him... He is sorta like a stalker... Now he starts to call me! Please help I don't know what to do?