On May 10, 1964, the Soul Giants, now featuring guitarist frank zappa after the departure of Ray Hunt, played a gig as "the Mothers" as it was Mother's Day, and also they felt it most appropriate since mothers was slang for motherfuckers. In 65, the label knows the slang and says to be classy and cover their bases and change it, remarking that 'necessity is the mother of invention'. The band took it literally and we all know they meant Motherfuckerz of Invention, which in the long run, made it that much better then just plain motherfuckers you know?