I didn't even get into anal play for fun, but originally for therapeutic reasons. Sure, I had a few girlfriends early on that would try fingering me a bit, but it didn't do much for me and they weren't that persistent, so I really didn't have much interest.
Now, I used to be as tight as a vice down there, and once even had a doctor giving me a digital rectal exclaim "Wow!" When I asked what that was for, they said everything was fine, but that I was really tight. This was okay when I was younger because I was very active and was basically a trail mix guy, i.e, lots of GI friendly foods. But when I turned 30 I got married, started raising kids and my stress levels went up.
That's when I started having a very painful issue that led to me getting diagnosed with a little understood condition that usually affects only men, proctalgia fugax, not once, but twice by two different doctors. Imagine waking up in the middle of the night feeling like you need to have a bowel movement, so you get up and head to the bathroom thinking "This is really strange in the middle of the night like this...", but nothing happens, no bowel movement, only a slowly growing cramp somewhere up your ass until you wind up on the bathroom floor curled up in a ball quietly moaning for it to go away, which it does after about 45 mins. It's basically a nighttime "charlie horse" up your ass.
So I went to a doctor to find out what was wrong. He took a good look around and said everything looked perfectly fine and that what I described sounded like Proctalgia Fugax. I asked what could be done about it and he basically said nothing except keep eating GI friendly foods, try to reduce stress in my life, and try a hot bath when it happens.
So months later when it happened again and I suffered for 45 mins because a hot bath did nothing, my wife at the time got concerned and recommended I go see another doctor that she'd met through one of her girlfriends at a social gathering.
Now this guy was offbeat himself, amiable and a bit of a jokester, married to an RN from Sweden, but well-recommended and definitely thorough. He did everything the first doctor did, gave the same PF diagnosis, and gave the same answer about what to do about it, but then added, "Now, I can't recommend this professionally, but there are reports that massage and gentle dilation can help to relax the muscles".
My wife wasn't too much into the idea so I started playing with plugs, which started being fun on its own, and after that marriage eventually ended, had a girlfriend for a while that was into it. She fingered me, toyed me, massaged me, and eventually fisted me until those muscles would yield and let themselves be stretched, and for years now I haven't had a single issue there at all.
I am not at all loose but definitely stretchable and I try to keep it that way using toys, some of them long to stretch deeper. I'm not even sure it's erotic, but there's definitely a feeling of relaxation that spreads throughout my abdomen afterwards and I'm convinced this is a good thing for me to periodically do. These are muscles after all and I guess I carry (or used to carry), a lot of tension in them. It's also kinda fun to do and there's the side-effect of massaging my prostate.
Sorry for being wordy, but it's a true story.