How About Trying to run a Music signal thru a Power Amp that isn't plugged into the AC outlet. Since the Power Amp Pilot light LED burned out a month before and you had it on your to Do List but later forgot you were going to do it and had unplugged it the month before but never did it.
Then one day You decide to Listen to some "Pink Floyd" and everything is on (YouThink) and for 20 minutes you play with all the knobs and switches to make it work.
Then you light up a cigar and sit back in frustration and some Neuron in your brain finally connects and your realize I better check the rest of my body parts to make sure there still there and then plug in the Amp