A Fonfon Ru is the name of an amphibiosan marriage partner (e.g. Kif Kroker is Amy Wong's Fonfon Ru). This term may be confused with Kif's reference to Amy being his "Smizmar" but a Smizmar is one that creates a love attraction in an amphibian that causes them to become pregnant. A Fonfon Ru is similar to a marriage partner, but without the legal binding contract, negating the need for divorce should they decide to separate.
According to Kif, the individual that brings on initial feelings of deep love and affection is your "Smizmar" or "significant other". Also according to Kif, the literal English translation for Fonfon Ru is "one who does not sleep with my superior officer".
- In "Proposition Infinity", Amy admits that she and Kif were not actually in a serious bond, as Fonfon Ru is not an official relationship; a weaker bond than true marriage.