A months duty, running the Sgt's Mess Bar at Akrotiri, was much sought after by some SNCO'S. When I was there in the early '60's a singly SNCO reckoned that he'd made enough to purchase a new car, after a stint in the Mess. On a Mess function night you had to be on your toes to ensure you got the right change. Of course as the night wore on this became rather more difficult!
Change for a tenner instead of the 20 offered was a common practice.