More on Two Fridays from Infoplease:

• Two Fridays - Two Fridays When two Fridays come together. Never (q.v.). Source: Dictionary of Phrase and Fable, ...
• Never - Never There are numerous locutions to express this idea; as- At the coming of the Coqueligrues ...
• Dictionary of Phrase and Fable: T - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "T"