1
general::
Phrase(s): fly the coop
Fig. to escape; to get out or get away. (Alludes to a chicken escaping from a chicken coop.) • I couldn’t stand the party, so I flew the coop. • The prisoner flew the coop at the first opportunity.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Escape, run away, as in After years of fighting with my mother, my father finally flew the coop. This term originally meant "escape from jail," known as the coop in underworld slang since the late 1700s. [Late 1800s]
American Heritage Idioms