Not like an imaginary light going off over your head like they have in the cartoons. An actual bulb. A little, teeny-tiny light bulb with two little prongs that stick out of the bottom and into the flashlight.
It happened a few weeks ago.
I turned on the mini-Maglite flashlight that we keep in the kitchen so that we can use it when we take the pup out for walks in the dark (not only is she black, but... well... it's hard to clean up after a dog if you can't see the ground) and after more flash than light it was dark.
I looked at the bulb and the lower half of it had turned a kind of milky white. (I do not mean it became the cow from Into the Woods. I mean that the clear bulb turned kind of translucent white.) (Feel free to google it - the cow, not the bulb.)
Today I finally had a chance to stop at the hardware store for a replacement. Just in time, really, because starting tomorrow - thanks to the end of Daylight Saving Time - our evening walks will be in the dark.
So I stopped in and said "I need a new bulb" and the guy behind the counter - who has obviously dealt with this way too many times responded with "Are you sure it's not the batteries?"
I showed him the milky white bulb (again - not the cow), and he said "Oh. Yeah..." and we headed off to find a new little, teeny-tiny light bulb with two little prongs. I stuck it into my flashlight and proceeded to try to blind myself.
Sadly, sometimes that other, imaginary light bulb is just a tad slower in going off.