Sorry for the lack of detail, but I heard this back when I was a kid.
In the South Pacific, by my recollection. I've heard "Polynesian long pig" as another euphemism. They might not have come up with the old favorite "tastes like chicken," because they have a long history of eating pork, but poultry not so much.
Of course, how widespread cannibalism ever was in the South Pacific is an open question; it's a common accusation made against rival tribes, and "natives," who aren't as dumb and "primitive" as we assume, love to play "mess with the anthropologist's head." Margaret Mead's early work has been called somewhat into question because of suspicions that the Samoans were pulling her leg.