It's a double reference to both Game of Thrones and Donald Trump's wall. Anything that we believe will provide safety evermore is a "wall". History reveals with mind boggling repetition that walls always fail. The walls of Nineveh, Carriage, Troy, Constantinople, Rome, Berlin, Jericho, Masada, Hadrian's , and China all fell and most very quickly. We know this, but in spite of this certainty we still "Buy the Wall" hoping this will be the first to work as intended. It won't.
The salesperson got her to Buy the Wall on that extended warranty.