I always wanted to know why sounding is so hot, it looks and sounds (no pun intended) extremely painful, i just wanna know how.

From what I know, sounding is actually perfectly safe if you know what you're doing, though I'm not into it myself. As far as urethral penetration goes however, I'm a hyper kinda guy (if it wasn't obvious) so I'm far enough detached from reality that sticking a dick into an even bigger dickhole doesn't really faze me. It's another hole to fuck, and when you cum you cumflate their balls, so there's that.

As a male, I can tell that sounding is a bit painful at the beginning, but if you're into it it can be good pain, and when you learn to practice it correctly, it becomes more and more pleasurable ! And it's a whole different feeling^^