A girl I was having an affair with 'squirted' on me once.
Well, it was more of a gush.
She was on me, riding in cowgirl, my cock buried deep inside her, she froze, said 'oh shit' and warm fluid gushed out all over my hips and soaked her bedspread.
She then kept riding until I came inside her.
Piss or not, I won't lie. I liked it. It added slipperiness to our action and felt amazing.