Who's pissing on your chips today?

[glatt]

That's happened to me before with a mouse. The solution is easy. I have a metal coffee can I keep handy. You pick up the trap with the mouse in it, drop it in the can, put it in the freezer, and then the next day, you take the mouse-cycle out of the freezer and drop it in a plastic bag to be deposited in the outside trash can. It sounds harsh, but it's the easiest and most humane way to do it. The mouse gets cold, falls asleep, and never wakes up. It experiences discomfort, but not as much as if you tried to kill it with a blunt object or something. Plus, it's very easy.