The symposium was sponsored by the U.S. Postal Service, which has seen so many outbursts that in some circles excessive stress is known as “going postal.” Thirty-five people have been killed in 11 post office shootings since 1983.
(deyim) Meaning: Go mad, go berserk. Origin: Originated in the USA in 1990s, where there were several incidents of people going berserk and shooting numerous members of the public in post offices
Go mad, especially from stress. [with ref. to cases in which postal employees have run amok and shot colleagues.]
[ 'gO ] (verb.) before 12th century. go (in the sense "become") + postal; from a rash of incidents, mostly gun violence, perpetrated by disgruntled U.S. Postal Service workers on co-workers in the United States, beginning in the 1980s (see quotations)