>>11399664
Many years ago I was so aroused by the idea of anal masturbation as a male that my first attempt was with a ~5.5cm diameter deodorant can and some vaseline, and I carefully put it up my ass. It was a kinda long can, but halfway in I had the strongest, most sudden orgasm ever until that point and I think that got me hooked up and rewired permanently. Like imagine being a shy teen that suddenly unlocked a way to orgasm like a subby bitch, that shit was a game changer.
Some people are simply more sensitive or wired different from the start, and sometimes it's easier to reach that "yeah that feels good" state after you've reached it once before.
Now that I think about it deep girthy insertions always drove me crazy, but it took me several years to learn to get off from shallow or purely prostatic stimulation.