Never one when you need one.

You are an operator at a nuclear power plant.

Your job is to be available in the case that manual intervention is required to keep the reactor from critically overheating.

There isn't much to do, since the plant pretty much takes care of itself, so you play a lot of tetris.

One day, the worse case happens. The core is getting too hot, and the automated rod insertion system has failed.

You suit up and enter the reactor area, and start grabbing the long 1 meter carbon rods, inserting them into the matrix of holes atop the reactor.

You have one hole left to fill, and go back to the rod bin, but all you can seem to find are rods that have been bent and/or other wise have manufacturing defects that cause them to be wavy. You curse your luck, running around the room in desperate search for one last straight rod.

You catch a glimpse through the glass into your control room and stop and stare at the panel of red indicator lights. You've never seen them that like, and it is nearly beautiful, which is good, since at least you were looking at something pretty before you and the plant exploded.