Greased

[Merna]

This is slang that originated with American soldiers during World War II. Many US troops were armed with their fully automatic equivalent of the [STEN gun], the M3 [submachine gun] which, because of its resemblance to the mechanic’s tool was called the ‘[grease gun]’. With the slightly macabre humour prevalent amongst those who are in combat, enemy troops killed by this weapon were referred to as having been ‘[greased]’.
It quickly came to mean killed by multiple bullet wounds from any type of machine gun. It was during the Vietnam War, however, that its use expanded and increased quite dramatically until it became used to describe any death in action against the enemy.
There is now some evidence to suggest that the word greased is being used to describe any violent death, even where this is not in combat and when it may even be an accident.