Seriously, never thot anyone would get turned on by watching someone piss outside. I better stop pissing in front of my buddies on our way home from the bars- maybe one of them will be tempted to drop to his knees. Don't think so. I think you have yourself a pretty rare fetish there, but good for you. Whatever it takes.
Why does it surprise you?
It's a deeply instinctual, masculine and very confident act! The sound of a heavy horse piss can be quite intimidating to some men, its teritorial and though a naturel function can be quiet a sublimianal social status statement and not to be too gross, but sometime the smell in a pub/club urinal can be so sweetly masculine and almost overpowering and intoxicating.
It might not really register with yourself as a straight guy just how dominatley male an act of pissing outside or with your mates, more so pissing outside with other males really is.
Count yourself as a instinctual male, lol.
As a smaller guy with frankly submissive tendencies that's easily intimidated by naturally, instinctually masculine (straight) men, it's an act that can trigger a number of primal and sexual responses.
If one of your mates was going to drop to his knees, the urge to do so would have been helped along by you taking a massive, horse wild jungle piss infront of him, lol.
It certainly makes me wanna call some men sir! And I fucking love it when my wolf takes a piss with the doors open.