A man, or a teen age boy, playing with his ass while masterbating does not have anything to do with your sexuality. There are some very pleasurable "buttons" inside your ass, especially your prostate, that will reward you with incredible sensations if you touch them with your finger, a SAFE object or if someone else touches it.
I have known many "str8" guys who even enjoy another man to F them just for the pleasure. If there are no emotional attachments or desires, I'd say that you are just enjoying your body. If you feel an emotional response towards another man/teenage boy, then you may be gay. Or bisexual if you have emotional attractions towards both sexes. The desire for wonderful sex is just human, not gay, str8 or bi.
Finding a woman who is willing to provide anal stimulation may be more of a challenge. But many females enjoy sex and want their male partners to have all the pleasure possible, so they are more likely to try it. Just remember men, keep your anal area clean. Scratch and sniff. If you wouldn't want to be there, don't expect another person to be there. And if you are using an object, the cleaner you are inside and out, the less mess you may have. Inexpensive enema bottles can do the trick.
Take it easy. Skin tissue around and inside the anus is sensitive and fragile. Use lube. Make sure fingers and/or objects are completely smooth. Make sure objects can be held and not slip in and out of reach. You don't need an embarrassing trip to the emergency room.
If you are a man, enjoy your anus.
