When you go into a restroom with flip flops and the person next to you is splattering piss on your feet. Or in rare occasions it can be your own.
My girlfriend asked me why my feet were all wet after leaving the restroom at the state fair. I explained to her that I was just pisstall whipped in there, but it's ok.. my feet were hot.
Someone who needs a piss so badly, that they have to piss where they stand. Then when they get dragged out of the club/bar for pissing on the dancefloor, they keep pissing on the way out, leaving a trail of piss in their wake.
Man, I almost fell over I the way to the bar, damn pisstrailer making a mess again