In my teens, using a kit built scope with a simple two wire power cord, no grounding, I had the scope "floating" across the series inductor in an ancient power amplifier's plate supply that I was probing. While contemplating the trace, not touching any part of the circuit, I placed one elbow on the scope's chassis and the other elbow on a signal generator.  !*! B+ across the elbows! I always observe the one hand in a pocket rule. I was ... er ... shocked that I was shocked. My elbows are still buzzing a bit from that one.