Brewer's: Hans von Rippach
[rip-pak ]. Jack of Rippach, a Monsieur Nong-tong-pas —i.e. someone asked for who does not exist. A gay German spark calls at a house and asks for Herr Hans von Rippach. Rippach is a village near Leipsic.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894