A question about platonic tickling?

Hi, I have a male friend who is really touchy-feely and likes to tickle me. I actually really enjoy it, it feels nice, and it's nothing inappropriate-- completely platonic. I was wondering, though, what's the best way to react to it? I really like when he touches me (mostly my back and my belly), but I don't just want to sit there like, "tickle me!" What would be the best way to encourage him to continue without explicitly saying it? Now, I usually just giggle a little and stay still, pretending to resist fits of laughter. Thanks for your help!!