The leftover urine that drips onto the pants or shorts after zipping up, giving the impression that one has pissed himself, or the water from a faucet that somehow ends up on said parts. Runoff is commonly hidden or removed by wearing long shirts or utilizing the hand-dryer while no one is around.

When you think up something brilliantly righteous while baked.

When you get fired on a job site.

To make a photocopy of something

when ejaculation has occured past it's maximum point

fresh cum trickling down an object

Runoff is usually for science, and runoff is used by a mountain. The running of water from the pure land up top.