Revusical.
The story is set in a beauty parlour in the inner-city area of Sydney. Stiffy and Mo become the new owners of the parlour and attempt to pass themselves off as medical men.
The principle characters are Stiffy (a rabbit seller), Mo (aka Sol, Stiffy's mate: see note below), Harry Summer (a doctor and owner of the beauty parlour), Helen Summer (his wife), Uncle (Helen's rich uncle), Mary O'Shea (beauty parlour employee), Mrs De'Vere (Helen's housekeeper and 1st Assistant Beautifier), Italian Woman (a patient in version 1), Bill Bender (a patient in version 2).
The songs known to have been incorporated into the revusical, as it was originally conceived, were 'The Opening Chorus', 'Lady's Band', 'Antonio', 'Skylark Love', 'Men, Men, Men', and 'Here's to Love' (also reprised as the finale).
It is possible that What Oh Tonight later became Manicure, Sir? (aka The Beauty Parlour). In addition to Stiffy and Mo, both these revusicals include characters called Helen, Uncle, Mrs De'Vere, and Mary. No production called What Oh Tonight has been identifed after 1916, further suggesting that Phillips changed the title (and possibly some of the storyline).