sleep with the fishes

The phrase "sleep with the fishes" is a colloquial expression typically used in crime-related contexts to convey the idea of someone being killed or murdered and then disposed of by being thrown into a body of water, typically a river or ocean. It suggests that the person's body will be hidden underwater, implying that they will become food for aquatic creatures or sink to the bottom, never to be found again. The phrase gained popularity through its usage in Mafia-related movies and literature.