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This is the Keep Your English Up to Date podcast from BBClearning English.com.

In this week's program, John Aito explores the origin meaning and use of the phrase go postal.

In Britain, the only hazardous situations

postmen are likely to encounter are having

their fingers caught in a vicious letterbox,

and perhaps occasionally being bitten by an angry dog.

How different things are in the USA.

Over the past 30 years there seems to have been a spate of killings by American postal workers,

who have gone on the rampage and shot their colleagues members of the public and police officers.

Apparently official statistics suggest that the murder rate at post offices is lower than that at other workplaces in the U.S.

Nevertheless, perhaps it's just the strange idea of homicidal postman, but for whatever reason

the image gradually caught the American public's imagination.

And by late 1993, we begin to find the expression Go Postal being used, meaning to rush

about in a murderous frenzy.

It got a burst of publicity with its use in the 1995 film, Clueless,

which boosted its popularity still further,

and it entered the general vocabulary of everyday American English,

in the rather watered down sense, become extremely angry.

As in Mom will go totally postal when she sees what you've done

...