I always thought "sandbagging" was the opposite of bluffing, i.e. concealing a good hand

Interesting, tsuwm...I can see the term being used in the context of 'hiding a good hand." Perhaps the term took on a different shade of meaning as it made the rounds among different gaming circles? I guess the real question, then, is what was the original intent of the slang term "sandbagging' in realtion to playing poker? Was it "concealing a good hand," "bluffing," or, perhaps, something else? Of course, the history of the term would only date back to the advent of the sandbag (as a flood prevention device, I presume?) . And when and where was it coined?