Is it normal my boyfriend likes this?

My bf has always loved kissing me and my body. He's really good for that because I like being kissed and licked. One time he spent half an hour just on my nipples. I love it too when his face is between my legs and his tounge is on me. But a few times in the last month he'd been pulling me to the edge of the bed and pressing my legs back so that I'm more on show to him. I thought he just wanted to get at me better but he started going a bit lower than he normal does until he wasn't even licking me out any more. His tounge was between my pussy and my ass and he was just running it up and down that area. It didn't feel bad or anything but it wasn't going to make me cum either.

Every time he did it he got more daring and went a bit lower than before. It was like he was seeing how close he could get to my ass. Anyways, last time, I didn't feel uncomfortable or anything but I wanted to know what he was doing so I said "Careful you don't end up in the shit, boy" like as a joke but he said he wouldn't mind, which is what I thought would happen.

Suddenly I got really curious about what it would feel like so I told him I wanted him to try it. It felt nice and all and I really liked the thought of him pressing his face into my ass crack and pleasuring that dirty part of me. He went crazy licking it but then he said he wanted to lick inside a bit too so he starts trying to press his tounge inside. Well, that didn't work very well so we just had normal sex then.

Anyways, when we were talking last night, he showed me a porn he had been watching. It was some girls with baseball bats up their ass and then when the bat came out their ass was still open and another girl put her tounge right inside and licked all inside the ass. Then he looked at me like he wanted to put his tounge right inside me like that. Like when he licks me out but my ass instead of pussy. It just seems a bit dirty and I'm scared to try it because of what he may want to do next. What if he wants me all wide open like that and wants to see me shitting? Like see the shit inside me coming out. Or worse if he wants his tounge inside while that's happening. I'm a bit kinky but I have limits too. But I also like when I make him do something dirty.