Oh and good old CRTs they can accumulate charge just on its own from the environment or hold charged for hours even days
Back in the early '80's I worked with NCR and was sent to their training center in Dayton Ohio to learn, amongst other things to repair the CRT terminals used with the mini computers - the instructor showed us how to discharge the tube before removing it (slide a screwdriver with attached ground wire under the anode cap), and then set it aside. He did this at 5:00 pm, at the end of the day, and when class resumed at 9:00 am the following morning, before he did anything else, he discharged the tube a second time, so we could all see the charge that had accumulated overnight.
Another one of his favorite tricks was to "walk" each student one-by-one through the power supply adjustment - he'd come over to your workstation, instruct you to put one hand in your pocket, hand you a plastic screwdriver and offer to hold the meter leads on the test points while you adjusted the voltage - the adjustment potentiometer was a few inches below the anode cap on the side of the CRT, right alongside your knuckles as you held that screwdriver, almost guaranteeing that as you twisted the pot, eyes on the meter display, that the knuckle of your pinky finger would hit the anode cap where there was just enough voltage to startle you.
The lesson there was to always be aware of exactly where you were relative to the high voltage components.