Meme: "Tacos" (v 2.0)
Scope: SFF chat — both (the now defunct) Mos Eisley and The Restaurant at the End of the Universe.
Originator: Unknown, but Ixrec may have explicitly described it first.
I love how "tacos" is the official safe word when engaging in rough chat
He also may have been the first to use it this way.
Cultural Height: November 2015 to present
Background: Born from the ashes of an unfortunate, older meme, "taco(s)" is now a hint to change the subject in chat to avoid unpleasantness.
Example:
@Axelrod And there we come to what are likely fundamental differences between us, and so I bid you a respectful change of subject. Tacos.