RIMJOB

My husband likes rimjobs... And I honestly love doing it to him. Not only bc it pleases him but because it turns me on badly. The few times I've done it I love to hold his ass cheeks, spread them and lick his anus. I know it sounds weird and probably gross to some of you... My husband is very clean and shaves his ass all the time so when I've done it, I haven't felt any hairs! I don't understand what's so sexy about this? Especially a woman doing it to a man? Most of the time I've had him laying down so I had to dig my head in there to reach his anus. But the last time I made him bend over (which he's never done before) and I licked his anus while I spread his cheeks wide open. He enjoyed it but I could tell he was shy. I think I heard him moan once. 
I always wondered why he likes his anus licked and why it turns me on?