Please check your change.

It was, of course, one of the oldest con-tricks in the book. Give excellent service and "accidentally overlook" giving the customers their change. I'd been pondering about the machines at Rome airport which wrap your suitcase in impenetrable cling-film. My suitcase will be kicking around Dubai tonight for several hours and I don't really trust the way modern cases are closed with hefty zip fasteners. Even though I have a broad strap around the case, it's dead easy to slip the zip back a few inches and take something out - I'd been doing just that on the train.

Convincing paperwork

So after much hesitation I decided to splash out €9 / £7.50 / $ 12 on having my case shrink-wrapped.
The guy who did it kept up a running commentary then when I handed him a €50 note he produced a receipt and fixed it to an insurance policy guaranteeing up to €3,000 compensation in the result of any damage. I decided it wasn't such a bad deal after all - until I realised when I checked in at the airline desk 20 minutes later, that he'd pocketed €41 change.
When I'd finished checking in, I returned to the booth and with a big smile said "Sorry, I rushed off and didn't take my change." I made no suggestion that there had been any deceit or dishonesty, and kept up my "anyone can make a mistake" approach while he made a big show of checking the takings in the till.
He handed me my change with a smile and a flourish and I apologised, then he apologised, then I smiled broadly and he smiled and shook my hand, and honour was satisfied.
Moral of the story - there's a way of playing just about any game.