massive, deadly voltages
I don't want to encourage any gratuitous tomfoolery, but I survived from my toddler days surrounded by CRTs opened up and charged, many live and operating. What you mainly want to avoid is the 20-30 Kv stored and accessible at the anode of the CRT itself. (That's a metal connector on the side of the fat part on the back of the tube, usually hidden under a wide rubbery cap.) Also pretty much the red wire hooked into that, and anything that it connects to. When the set is unplugged and capacitively charged, it's only like a really good cattle prod; The trick is to arrange your body/arm whatever so that the spasm doesn't drive soft tissue into sharp metal bits. The worst I've ever done was an occasional scratch or small piercing. Maharishi Bob got a 3mm blackened hole through a thumbnail once, but he was always pretty free with reaching into live sets. My dad's electric fence charger has more knockdown power, in my experience. Oh, and keep one hand in a pocket or behind your back, if you REALLY try, you can actually get killed.