"Blue raspberry" is probably a flavor made up by chemists. They must have been trying for blueberry, but when that flavor proved too elusive, said, "Well, we're not gonna get blueberry, but this batch here tastes a bit like a cross between blueberry and raspberry. Let's just say it's 'Blue Raspberry' and call it quits. Sure, there's no such thing as a blue raspberry, but if there was, this is what it would taste like. Trust me."