First time I saw it was in a game from Japan where it meant special, but it’s funny that it’s grouped in with the A-F scale, which doesn’t stand for anything, which itself is funny because it skips E for no apparent reason.
‘Country’ music. There is a specific style of country which is the most prominent, and it is so stupid it’s a parody of itself. It’s what you would make if you wanted to make fun of Americans, but made and listened to in full sincerity. Then there is the rest of it. Johnny Cash is technically classed as country but there’s no way I’d class him as being anything like Garth Brooks. More modernly, Poor Man’s Poison uses country sounds, but doesn’t bemoan the loss of their truck, dog, and wife with the same chord progression that hasn’t changed in decades.
You, too, are 0 calories if we eat you in small enough bites.
The vast majority of premeditated murders are not done by someone who just wants to kill, and so looks for someone to kill that will be more morally defensible. They are done by people who really want to kill a particular person or group who they hate, or view as a threat. Serial killers are also generally not doing the Dexter thing. They have their own targetting preferences that aren’t usually aligned with social morality.
So, no. Probably no one ever has done that.