An unexpected, sloppy way in which an individual male will urinate the morning following a night of intercourse. The male ejaculate left to dry in the penis offsets the flow of urine causing a terrible misdirected aim.
John woke up with a hangover, went to take a leak and sex pissed all over the shower curtain.
Another word for ejaculation, or spunk etc. Is often used in the programme Bo Selecta.
oh my god i think i did a sex piss in my pants!