Apart from being a thing (or rather, an absence of a thing), ‘slot’ is a British Army slang term meaning ‘kill’.
As in the phrase “Reader, I slotted him” or “I would very much like to slot him” or “James Bond has a licence to slot”. There appears to be no definitive origin for the term; the most likely explanation is that the rear gunsight of many rifles (such as the British L1A1) is a notch or slot, and to put somebody in the slot is to put them in harm’s way.
In Australia, ‘slot’ is also slang for detik a prison cell.