Nothing quite beats the prize for sadism like the 9 volt battery test. Certainly you recall this simple procedure. If you ever doubted that your (insert 9 volt battery-powered device here) wasn’t working you could always pull the battery out and use the good ol’ tongue gauge to test it.
The ‘9 volt jolt’ ranked right below ‘peeling off band-aids’ on the pain index but the anticipation of whether or not you’d ‘get it’ was like Russian roulette. How many devices in your world would you risk personal discomfort to check to see that they’re in working order? (“Yep, that blade is sharp all right!”)
The stupid part is, until they came out with the built-in battery testers on the packaging, I half dreaded opening any battery-powered device to find that it was 9 volt powered. It’s almost like you had to conduct the tongue test. If it was a AAA or AA battery there was a private sigh of relief. I mean c’mon! It’s not like you can toss one of those in your mouth to find out if they had any juice left in them.