Bunk (noun)

1. A bed, typically one stacked on top of another, as in a ship or prison.
2. A story or idea that is absurd or false.

Origin:

Early 19th century (originally us): of unknown origin.

Examples:

1. The sailor was exhausted after a long day at sea and crawled into his bunk for some much-needed rest.
2. The prisoners slept in bunks stacked three high in the cell.
3. His claims of having won the lottery were obviously a bunk.
4. The conspiracy theory was pure bunk.
5. The soldier was assigned to the bottom bunk in the barracks.