Some girls lose their bladder function when they orgasm so it's real. Yes it's piss.
Yup, I've had many girls piss all over the place due to a crazy long stimulation session on their g-spot. There are people who teach you how to do it. The first time they release you know it's real by their reaction, they are quite embarrassed and/or surprised. My GF doesn't like to talk about it, but squirts all the time when i pressure her g-spot the right way. There is a technique to do it and every girl i tried it with ended up pissing themselves, but most will stop you as i think they feel it coming. I think it's glorious!
The bad part is, once they learn it they will do it on purpose to impress you, if they really are being set as the receiver.
I think it's fucking hot, but i'm also a degenerate that loves exposing women's deep need to be dominated. I will do things to women that most men don't, as i know how to drive their inner spirit to places that most people consider taboo. But they all love me more than Jesus once i show them the way.
OP - I've almost had a dry cum a few times when i was severely dehydrated and already busted a few nuts that day. And yes to the dude that said a very tight vag can block your nut, i've had that happen a few times with a girl that could flex her vag to be as tight as a vice, my GF is practicing this currently and it works, she can clamp on my cock like pair of channel locks.