To become extremely angry, possibly to the point of violence.
People in domestic disputes get crazy. When kids and spouses are at stake, folks go postal, grab knives, get looney.
Fred Reed, "A domestic dispute is coolly unraveled," The Washington Times, January 8, 1996
Postal Service employees are no more likely to "go postal" than are other American workers, according to a national study released this week. . . . Researchers found that the homicide rates at postal facilities were lower than at other workplaces. In major industries, the highest rate of 2.1 homicides per 100,000 workers was in retail. The next highest rate of 1.66 was in public administration, which includes police officers. The homicide rate for postal workers was 0.26 per 100,000. The Most dangerous occupations: taxi drivers and chauffeurs, with a homicide rate of 31.54 per 100,000 workers.
Bob Dart, "'Going postal' is a bad rap for mail carriers, study finds," Austin American-Statesman, September 2, 2000
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.
Karl Vick, "Violence at work tied to loss of esteem," St. Petersburg Times, December 17, 1993
Postal workers are the archetypal pissed-off employees. That reputation began on or about August 20, 1986, when a disgruntled postal worker opened fire on his co-workers, killing 13 of them. Over the next seven years, there were nine more such incidents involving postal workers, and a total of 34 people were killed. These gruesome statistics are the source not only of postal workers' violent reputation, but also of the phrase go postal that is still used today with dark humor.
The good news is that the workplace homicide rate is going down. According to the Bureau of Labor Statistics, there were 1,080 workplace murders in the U.S. in 1994, but "only" 677 in 2000 (an increase from the 651 recorded in 1999). This mirrors the overall rate of workplace violence. Although there were over 802,000 incidents reported in 2000 (according the U.S. Bureau of Justice Statistics), that figure is down from the 1,064,000 incidents reported in 1996.