The meaning of this phrase is disputed among historians. Some believe it originates from a secret cult of people who dress their cats up like famous Soviet leaders and put them in a room, meanwhile the owners sit around and drink tea. Revisionist historians believe however it is a phrase used to describe a prolonged period of wild activity.
Historian 1: Then they all sat around drinking tea and discussing the economy at their strange Russian cat party.
Revisionist Historian: "That was a mental Russian cat party of a weekend!"