French leave

A French leave, sometimes French exit, Irish goodbye or Irish exit, is a departure from a location or event without informing others or without seeking approval. Examples include relatively innocuous acts such as leaving a party without bidding farewell in order to avoid disturbing or upsetting the host, or more problematic acts such as a soldier leaving his post without authorization.

The phrase is first recorded in 1771 and was born at a time when the English and French cultures were heavily interlinked.

In French, the equivalent phrase is filer à l'anglaise ("to leave English style") and seems to date from the turn of the 19th and 20th centuries.