1
general::
Phrase(s): push the panic button
Go to hit the panic button.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, press the panic button. Overreact to a situation, as in Don't worry; Jane is always pushing the panic button, but I'm sure the baby's fine. This term originated during World War II, when certain bombers had a bell-warning system so that the crew could bail out if the plane was severely hit. Occasionally a pilot would push the button in error, when there was only minor damage, causing the crew to bail out unnecessarily. By 1950 the expression had been transferred to other kinds of overreaction.
American Heritage Idioms