The piss shot happens either while getting a blow-job
or receiveing a wank
, near the crucial point of ejaculation
you cover the tip of your penis
with your foreskin, then hold it closed with your fingers, it is crucial she is on her knees and close to your penis,start pissing with the foreskin still closed, within the next few seconds the foreskin will expand and eventualy your fingers wont be able to hold it all back and both the piss and cum explode on her face, while shes realising what happend you have to walk away,with your pants down if nessisary, and without looking back say: "you just got pissed-jobbed"