When you decide you have to shit, sit on the toilet, then mistakenly pee first. When you shit, the weight of the poop splashes the piss (and water) onto your ass and legs.
/ˈkəʊpɛk,ˈkɒpɛk/
noun An edifice or place dedicated to the service or worship of the NeonDemon where you pay your respects via the acquisition of regalia