The origin story describes William Lane of Los Angeles attending a football game on a Friday night in 1941. The teams were from two Catholic schools. Lane met a hot dog vendor who was having a bad time: not a single person had purchased a hot dog.
That does make sense. Most of the fans would be Catholic and Catholics did not commonly eat meat on Fridays. Fish, though, didn’t count as meat. So there was an obvious if unusual solution possible.
Lane consulted a friend named Curt Schirmer, who knew how to make sausage. Together, they experimented with the difficult process of making a hot dog made out of tuna that didn’t stink, didn’t taste like fish, and would congeal.
Lane, Schirmer, and investment partners developed Tunies, as they named the product, and manufactured the hot dogs in a plant in San Diego starting in 1957. The firm survived until 1967 and most likely collapsed after Pope Paul VI ended the Friday fasts of meat during that same year.
-via Discontinued Foods