My dad sold these at his store, they had all kinds of weird stuff, still do. I had one of those "Spy Pen" radios, and used to listen at school a lot, as the teacher I had at the time was sick with some nearly always fatal disease. I grounded it to the radiator that was next to me, I changed the blue ground wire to a green one to blend in with the pale green of the radiator and bottom half of the wall. Worked pretty well, listened to CKLW (most days), WSPD, and sadly, WTOD, a country station that wasn't far from school covered up a lot of much better stuff . Suddenly one day, one of the kids in the classes mother was our teacher. She caught me pretty quickly, but she didn't realize I had an almost endless supply of them at home, probably at least 30 of them, so I let her take a half dozen of them without any complaints until mom got a call and I had to quit using it. I was checked to see if I had an earphone in my ear for months. She stayed until almost the end of the year, and one day our normal teacher was back, totally recovered and she told us about how she almost died, etc. She ended up living to be like 95.
I still have one someplace, it's red with a white "cap". WTOD was still blasting in on it until I moved, now it's some country station in Mich, about 3 miles north.
