Green’s Dictionary of Slang

it’s one o’clock (at the button factory) phr.

also it’s two o’clock..., it’s three o’clock..., ...at the waterworks

advice to a man that his fly is open.

[Aus]D. Niland Call Me When the Cross Turns Over (1958) 57: ‘It’s one o’clock, Bow-tie,’ Barbie reminded him seriously. ‘Oh!’ he said, and did up the button on his fly.
J. Beatty Jr 1 O’Clock in the Button Factory: The Amer. sense of humour – an outrageous inquiry into what’s funny, what isn’t...and why [title].
R. Sussex University of Queensland Langlab 1 Feb. 🌐 I was reminded, when thinking of euphemisms, that I haven’t heard for a long time the phrase ‘one o’clock at the water works’, which was a delicate way of telling a gentleman that his fly/flies was/were undone. Does anyone have other euphemisms for this state of disarray?