My first recollections
I must have been about 10 years old. I was still taking baths since our house did not have a shower in the hallway bathroom. I recall that when I washed myself it felt good to wash around my asshole. Once I just slipped my finger in there and it felt good. I also got an erection. I was too young to fantisize about girls, in fact I didn't know what you did with them and had not seen any naked photos of them. So this was how I could make an erection happen.
Once of my toys was a plastic submarine that would shoot tiny torpedos. These little guys were about a 1/4 in diameter and about 2 inches long. You can guess where this is going. It was just a few moments thought to figure out these little guys might feel good in my butt. So I put one in and got an instant erection!
For many months those little torpedos, and lots of bubbles made bathtime funtime. The bubbles hid the erections from my Mom, while I would sit in the tub for 30 minutes or so with one torpedo 'missing'.
This began a long term love affair with my butt that continues today. More objects and more fun in part 2.