be, go, etc. out/out of the window
go out the window
To be forgotten, disregarded, or lost. One member of the audience started shouting at the speaker during the presentation, and all sense of decorum went right out the window. Once the government deregulated the industry, expensive safety precautions were the first thing to go out the window.
go out the windowBRITISH, AMERICAN or
go out of the windowBRITISH
COMMON If something such as a plan or a way of thinking or behaving goes out the window or goes out of the window, it suddenly disappears completely. Finding myself in a country with so much delicious food, all thoughts of dieting went out the window. When people are so desperate to do something, common sense often goes out of the window. Note: Other verbs such as fly are sometimes used instead of go. Three years later she met Mick, and her good intentions flew out the window.
go out (of) the window(of a plan or pattern of behaviour) no longer exist; disappear. informal
1998 Economist In the ensuing struggle between the two groups [of councillors], the public interest goes out of the window.