Based on my own experience, a now dead generation of the kind of folk that ran the Empire used the word quedo or quedos (that is how I assumed it was spelled based on the pronunciation) to describe unspoken/unrecorded acknowledgement of merit that, in extremis, could divert an otherwise deserved "rocket". Earning quedos was part of building a successful career.
I don't know at what point it entered US slang, or how. But if US-usage doesn't pre-date February 1943. I have a fairly good idea of the how/why. The term has been in pretty regular use in the UK military for a long time.
Originally, like so many other phrases, it could have its roots in India. In a world where people live in each other's pockets, quedos, like bitcoin was transferable and spendable in ways that are not always readily apparent.
So there is an interesting tradition as far as the modern kudos is concerned.