When I bought my house, there was a surface mounted light switch on the wall. The room was wallpapered in the 1960's, and when I looked really close, I discovered that the wire used was lamp cord, and the wires were neatly papered over and covered. After I turned off the power to the circuit at the (then) fuse box, I pulled the wires loose from the wallpaper. They ran up and across the ceiling to the light fixture, and there were 2 splices in the wires... I think someone used a couple of extension cords to make this connection.
What I love, is that the inspector missed this when I bought the house.
I've rewired the entire house, with the exception of the knob and tube wiring in the attic, now, and the K & T wiring is on its own 15 amp breaker. The only things running on the old wiring now is a couple of ceiling fans.