Green’s Dictionary of Slang

(US) the average, typical woman.

1977		Aviation Wk and Space Technology 9 May 70: Those of us who have watched the Apollo or Viking projects financially and technically struggle...may have a different perspective on our numerous space accomplishments than does the general public, be they John Q. or Jane Q. Public [HDAS].
1999		J. Bentley Programming Pearls 24: We will ship your order to Ms. Jane Q. Public 600 Maple Street Your Town, Iowa 12345.
2002		P. Lafferty Single Stock Futures 230: Everyday investors — John and Jane Q. Public—will have a chance to be exposed to a world they may never have even considered before.