The only one I know of that’s no been covered so far comes from my EMT experience. Well out of earshot of the family, a dead person we have to deal with is refered to as ‘negative patient’.
DRT - dead right there
DFO - done fall over
Dirt Dart - aircraft into the ground [generally military]
Winners of the Darwin Award [like those 2 marines playing quickdraw in the barracks…]
Relieving the Thresher on station [if you are nervous about the quality of your boat/crew]
[Dr. McCoy Voice]: He’s dead, Jim. [/DMV]
Or it could come from the sound of the “death rattle” they used in the 19th century. Croak can also mean to kill someone.
Snuff out could refer to how people used to extinguish candles by pinching them with their fingers, as in “Snuff out the candle.”