He is interested in you more than just a friend. I had a guy do the very same thing to me. He would make fun of me (in a playful way) and ALWAYS would come up and poke me in the ribs. It got to a point where I asked him to stop and he didn't. I thought he didn't like me until he asked me out. I was shocked. I didn't go out with him because he made such a pest and I really didn't like him too much. That was too bad. I guess, from what I gathered later, he really did like me.
Hope that helps you.