It's neither squirt or piss. I saw a mid 90s amateur porn that showed how it's done. You notice how a lot of the times the water looks pure. That's because it is. It's bottled water inserted in the vagina. The girls hold it in with their vagina muscles. Then they release(spray it out-push it out) They do it before they go on camera. The girls will sometimes use milk or Half+ Half(creamy, thick)+ put in a small loosely wrapped plastic bag+ insert it in vagina. Then masturbate until the cream becomes loose from the bag+ comes out of vagina. People think its cum. It's not, it's milk. That's it I'm done. It's late. Have a good night!
We call that taking a piss!