Everyone is correct.
G7#9 describes the specific chord you are playing. However, Tony is also right: under Jamey Aebersold/David Baker "chord/scale" theory, G7#9 is a shorthand way of denoting the "altered" or "Super Locrian" scale (the 7th mode of Ab melodic minor). Under this system, you could add a b9, #11, and #5 to the chord and STILL acceptably write it as just "G7#9," rather than the full "G7 b9,#9,#11,#5."
But it wouldn't sound half as funky.