Can someone (perhaps older than me (I'm 38)) explain this sentence? I have no idea what it even means to "beat on" a flashlight. You push a button, it turns on. What is there to "beat on"?
edit: Weird. I guess I've never used a cheap flashlight, because I've never had this experience.
This is due to the bottom-of-the-barrel cheap components and construction of low cost flashlights. Often the components aren't lined up correctly, or the switch isn't making perfect contact, or the spring is too compressed to push the batteries up against the positive contact (which is often the base of the bulb). I can't count the times I've had to disassemble and repair a cheap plastic flashlight right after opening the package, just to get it to turn on and off reliably.
Just in time to see the antagonist right in front of them.
Sometimes, things in older flashlights aren't all aligned or for some reason the circuit just can't complete, so you smack it on your hand and it ... just works. Unless the batteries or bulb truly are dead. Then you just have a sore hand that you can't see.
I think it has to do with cheaper flashlights that basically consisted of not much more than a plastic tube, a bulb, and some springs for the electrical contacts. Because the tolerances were so poor, the battery terminals would often lose contact with the metal springs. One solution would be to open the flashlight up and re-set the battery. But usually, giving the case of the flashlight a few whacks was enough to bounce the battery back into a place where the circuit would be completed and the flashlight would turn back on.
It's the gentle, inquisitive wiggle as you stare directly at the bulb which causes it to turn back on.
For related reasons, never look down the barrel of a gun which has not been sufficiently disassembled. There are no answers there.
Marginal batteries: Sharp acceleration shifts internal contents just enough to provide for a more energetic discharge.
In short, yes, it's a real thing. Especially when Dad insists on keeping his 50 year old flashlight and on eking every last electron out of each set of batteries. ;-)