I am a straight man. I have always played with my ass, and only found relationships satisfying if the woman is into my bottom. I started fingering my anus soon after I started masturbating to orgasm at age 11. I lost my anal virginity when I was twenty to a woman several years older than me. We were a couple for a few years when I was in college. She was very assertive and had a thing about male asses. She fingered my hole all the time and spoiled me for any woman who wouldn't. I've had other women do it too, including a woman I fell in love with when I was still in my twenties, who was the first to lick my anus, and the first who took my cock up her ass. My wife likes to lick and finger me. The one thing she won't do is use toys on me; I own a collection of butt plugs, vibrators, dildos, and prostate massagers that only see action when I'm alone masturbating. She doesn't like the idea at all, though she likes me to lift my legs or bend over so she can spank me, bite my buttocks, lick my anus, lubricate it and insert a finger or fingers to pleasure me. She knows about the prostate and how to make me have a really intense orgasm.
The phobia a lot of men have about their asses is beginning to weaken, though it's still there as seen by some of the responses here. Enjoying having your anus played doesn't make a man gay. Wanting to have sex exclusively with men makes you gay. There's this whole stupid stereotype that equates being penetrated with homosexuality...you don't hear people saying that a man who wants to penetrate a woman in the ass is gay, or that a woman who likes receiving oral sex is a lesbian. Sexual orientation is about who--man or woman--you want to have sex with. Whatever kind of sex. It's not about who does what and how.
The asshole is highly erotic. Having it licked or penetrated stimulates countless nerves. Besides the prostate and seminal vesicles, which produce semen and respond to stimulation of the perineum (the area between your balls and anus) as well as to penetration, there is also the base of the penis, which goes deep into the body. That responds to anal play too. If you're concerned about cleanliness, have an enema and wash up. Use lots of lube when you stick things in. Enjoy! (And don't listen to the uptight idiots with their stereotypes and phobias. Butt play rules!)