...Thanks, Gary. Id heard this but never saw anything in print about it . . ;-) This is the version I heard. .. .
<< My French teacher of 40 years ago reckoned the term was a mishearing of 'au quai' (literally 'on the quay'). So "vos baggages sont au quai" (your luggage is ready for loading) would be a reassurance that there was no problem.
<< The item that Mysturji recalls may have been a 'colouring up' of this (unconvincing) story – a cargo of trouble-free sugar would be 'au quai' in any French Caribbean port. >>
Here's an interesting article about the origin of the expression OK. It started in Boston back in the early 19th century and has since become universal.