Fish or cut bait
There is some uncertainty about the precise meaning of this phrase. Some use it to mean 'make a choice about what you intend to do'; others have it that it means 'either get to work in a productive manner or do something else and let someone else work'. The second meaning, which I favour, and which is more common, is similar in meaning to 'put up or shut up', or the 20th century US vulgarism 'shit or get off the pot'.
'Fish or cut bait' is of US origin and, of course, derives from fishing. Cutting bait is a straightforward literal term, that is, chopping up bait to attract larger fish. The phrase began to be used figuratively around the middle of the 19th century; for example, this piece from The Opal: A Monthly Periodical of the State Lunatic Asylum [Utica, N.Y.], 1852:
But delicacy is attacked with Epilepsy in depicting so faithfully the results of sane life; the truth needs no commentary; farther, the moral turpitude of such customs, among those who profess so loud, and long, their fortunate position among folks; and hence, their infallibility bids him who indulges his time to pass in their narration, to fish or cut bait."
The meaning of the phrase isn't exactly clear from that extract - the magazine was edited by the patients.
'Fish or cut bait' came to the public's consciousness following a widely reported case in the following year, president over by the American Judge Levi Hubbell. It came up in 1853, in a legal dispute over land ownership between US Attorney General Caleb Cushing and a William Hungerford. Cushing was displeased with Hubbell's conduct of the case an threatened to have him impeached. Hubbell's response was:
"Judge Cushing has commenced a suit in the United States Court. Judge Cushing must either fish or cut bait."
The journalists who reported the case, along with the lawyers in court, had clearly not heard the phrase before and were at a loss to understand what the judge meant; for example:
The Madison Daily Argus And Democrat, 1853: "What the precise meaning of that term is, I do not know."
Milwaukee Daily Sentinel, August 1853: "There was some discussion amongst counsel, without any conclusion, as to the meaning of this phrase."
Milwaukee Daily Sentinel, October 1853: "I leave it to you to interpret that phrase from the testimony of the case."