He wants to eat my ass??

I don't know what else to do than to start this bluntly. My boyfriend has, multiple times, told me he's going to eat my ass. He says it turns him on and all, but he's never done it before. Asses are asses. Like where shit comes out. He told me he knows what he's getting into but it still seems weird to me. I'm pretty down for whatever but I'm just worried it'll end horribly. Anyone have any sort of advice or experience? I'm so terribly lost I don't even know what to ask for at this point.