(Brought up by a Russian YouTube link which is NOT about Stalin).

More from other places? I've seen two nominations for "Stalin's favourite song" - one is the lugubrious Georgian my-girlfriend-died ballad "Suliko"; the other is a much more interesting Azerbaijani song "Pencereden tas gelir" (the stone came through the window) which Stalin apparently used as a code when in jail in Baku in 1908, for his comrades outside to signal when they were about to biff a pebble with a message wrapped round it through the window of his cell. (There is a very long description of the background on an Azeri website which I could translate if anybody showed sufficient enthusiasm).