like turkeys voting for Christmas

The story

Because turkeys are commonly eaten at Christmas, turkeys voting for (an early) Christmas would be hastening their own death. The phrase is thought to have been coined by the British Liberal Party politician David Penhaligon (1944–1986) who used it to express opposition to the 1977 Lib–Lab pact. It was popularized by the British Prime Minister James Callaghan (1912–2005) who used it in the House of Commons in March 1979 when his Labour Party lost a vote of no confidence: see the 1977 and 1979 quotations.

First known use, by meaning

• from 1977 Self-defeating; serving to bring about a situation detrimental to the performer of the action.