A Jimmy
Job is when you do
something on the rush, in other
words, an improvised thing. A more formal equivalent expression would be To do something on the run
In Sense8 Season 2 episode 3 when Sun was breaking out of
prison Nomi and her friend Bug were trying to
hack the system, then Nomi asked bug :
Nomi: Bug?
Bug: I got something. Bit of a jimmy-
job