daddy? boyfriend?

So me and my bf had the 'daddy' discussion and he wants me to call him it. I'm not against it but I feel a tiny bit awkward (about how to start calling him it). And tbh when he says it, It turns me on? We have a Dom/sub sexual relationship, me the sub of course. How do you ladies feel about calling your bf 'daddy'? PS: I do not in anyway call my dad 'daddy', nor have I ever. My bf said to think of it in the way 'I belong to this man' not the father way.