Secret message - in the fur of a hamster
In Péter Bacsó's absurdist classic film The Witness, the communist state accuses the protagonist and his disgraced friend of passing "secret messages in ground squirrels skins" to the frogmen. According to the story, the two characters do indeed come into contact with the "dam's greatest enemy, the ground squirrel", beating the crap out of a (european) hamster.