Set it to 4625 USB and listen to the creepy Russian Buzzer UVB-76. There has been speculation that this is part of the dead hand nuclear response system, though

Set it to 4625 USB and listen to the creepy Russian Buzzer UVB-76. There has been speculation that this is part of the dead hand nuclear response system, though this theory has seemingly lost credence more recently. I also didn't notice any mention of it in David E. Hoffman's book, but no matter what it's actually for it is interesting and just a bit unsettling, especially late at night.