How Do I ask him?

1. He doesn't like for me to grab his ass. It's off limits, but he LOVES ❤ grabbing mines. How do I ask him to put it in my butt? I'm scared he'll not want to do it or anything. He wants to taste me and I'm not too into bjs but I want to try it in my butt! What are some sexy ways to tell him ? How do we even go about this convo I think he'll be turned off because he doesn't like when I touch his ass.