Out of pocket is a phrase with multiple meanings, that contradict each other and are separated by the geographical origin of the speaker.
In the British sense of the expression, to be “out of pocket” is to be struck by poverty, resulting in an empty purse.
In the predominantly American sense of the phrase to pay “out of pocket” is to buy something using cash, which is predominantly held within one’s pockets.
The first documented use of the phrase comes from 1679, used for expression bankruptcy.
This served as the foundation of the expression in England, resulting in the present day disconnect between the British and American application, the latter of which first showed up in 1885.
“Out of pocket” has many varied meanings from region to region, speaker to speaker these days, as is shown by the many differing Urban Dictionary entries.
It was first defined on the online lexicon site in 2003, with a large amount of other explanations having been uploaded since then.