shortwave "numbers stations": creepy spy stuff
When I was a kid, my folks got a multi-band radio that picked up not just AM and FM, but shortwave and audio channels from TV. (If memory serves, they got the radio with a big stack of game tickets from an arcade in Atlantic City.)
While we mostly used it to listen to Johnny Walker or Brian and O'Brien in the mornings, or listen in on TV shows while in the tub in the evening, every once in a while I'd fool with the shortwave. Sometimes I'd pick up a weird channel with someone reading numbers, ghostly voices reciting nonsense.