Dave Barry is an American humorist, whose quotes are to be found on the internet, and are well worth browsing for an hour or so.
Here's an extract from one on electricity, that concerns eye laser treatment:
".....in the past decade scientists have developed the laser, an electronic appliance so powerful that it can vaporise a bulldozer 2000 yards away, yet so precise that doctors can use it to perform delicate operations to the human eyeball, provided they remember to change the power setting from "Bulldozer" to "Eyeball.""
So remember: if you are to have laser treatment, just take a peep over the technician's shoulder to make sure the switch isn't at 'Bulldozer'!
Jim