My man got drunk and asked me to play with his ass!

My husband has said since the day we started having sex that I would never be allowed near his butt. We have had plenty of butt sex the other way (him in my ass) but I've never ventured anywhere near his because he's made it clear that he didn't want that. Until last night. He had a few beers and I was giving him a blowjob. He stopped me and asked me to come kiss him and asked me if I ever thought about playing with his ass. I said of course and one thing led to another next thing I know I had a finger in his ass while I was bringing him to orgasm with the blowjob. Can anyone give me some tips on what to do down there in the future? We obviously used lube but other than that I'm lost and needing some guidance on how to make it feel awesome for him.