If your name's Donald Trump Jr. and old retired couple having sex videosyou start tweeting about socialism, it's not going to go unnoticed.

On Halloween night, the president's eldest son decided to use his daughter to make a political point.

Here's the original, now widely-mocked tweet:

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A lot of people, like historian and author Kevin M. Kruse, pointed out the big flaw in Trump Jr.'s logic.

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Then, on Wednesday morning, J.K. Rowling waded in:

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If this were a wizarding dual, Donald Trump Jr. would just have been expelliarmus'd.

Hard.