They should be shot
What's the origin of "they should be shot"?
Presumably that the people in question are so unspeakable that they deserve the ultimate penalty of death by shooting.
DFG
In the Western US I get the feeling that "they should be shot" is used facetiously more often than seriously. If kids were to repeatedly leave their toys in front of someone's apartment door "They should be shot." might be an appropriate string of expletives.