I'll go first. Mine is the instant knockout drug. Like Dexter's intramuscular injection that causes someone to immediately lose consciousness. Or in the movie Split where there's the aerosol spray in your face that makes you instantly unconscious. Or pretty much any time someone uses chloroform.
Rightful heirs and similar shit. I hate this monarchist propaganda with a passion.
For all the faults of the final seasons of Game of Thrones, I appreciated that this was the consistent message in the novels and show: beware powerful men and women, and those who aspire to be, because your interests are not their interests. The government formed at the end of the show was basically the least-worst option available in a feudal society.
Even the attempt to improve society somewhat was mocked, given the swerve treatment https://redsails.org/the-swerve/ and even "winter is coming" which was supposed to be some big imminent ignored menace was undone in one cheap stab so the nobles could continue status quo enjoyment minus a melted throne.
The overall muddy message was "sure everything is shit and covered in blood and shit, but attempting to improve society somewhat is naive and stupid and will maybe make things worse or just (at the very finale) be laughed at by your masters. Just go along with their whims."