What is the definition of Canadian Missiles?

"Canadian missiles are like the ultimate sarcastic snowballs - they're supposed to shoot down enemies, but somehow they just end up knocking over a bunch of maple leaves and sending the local wildlife into a panic. Or, like, into a panic about who's really in charge of their own country's defense."

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Edgy example sentence: "I ordered a 'Canadian missile' of a cup of tea, and now I'm convinced the universe is plotting a global maple syrup rebellion."