Asking Is Hard
Speaking as a guy, I never wanted to be the one who asked. It was so hard, putting yourself out there, worrying about being rejected or laughed at.
Just Be Friends
I think at your age that friendship first should be the rule. In other words, keep calling him and being his friend.
You can ask him out as a friend, first and it won't be seen by everyone as a "date." You could even ask him out with your friends.
Whanking Means He's Interested
If the "whanking" comment is true, it sounds like he really is interested in you. So, I think that just be being together that the chemistry can happen.