I would go cold-hearted killer on him. That sort of game-play is childish at best. I think you did right by not responding right away. You need a cold, calculated, and unemotional response. The guy is trying to push your buttons, you have to show him you ain't going there.
The cold-hearted killer part is where you tell him that if he had some girl he was into, you would think it totally uncool to play the same sort of shit with him as he just did with you. So he's got to make a decision. If he wants to play 13-year-old on the playground, you are out. Nice knowing ya.
But if he's actually trying to be a serious friend, don't go acting like you just came off your meds. You draw the line about what you will and won't tolerate as stupid pranks. Or worse: a friend messing with a girl he knows you are into.