on your Jack

on (one's) Jack

old-fashioned On one's own; abandoned or isolated. Primarily heard in UK. Coming home from the war, many veterans felt as though they were on their Jack as they tried to re-enter civilian life.
See also: jack, on

on your Jack

on your own. British informal
This an abbreviation of the rhyming slang expression on your Jack Jones .
See also: jack, on