It all begins here.

In 1791, a Dublin theater owner named James Daly made a bet that he could introduce a word into the language within twenty-four hours. He then went out and hired a group of street urchins to write the word X, which was a nonsense word, on walls around the city of Dublin. Within a day, the word was common currency and had acquired a meaning(since no one knew what it meant, everyone thought it was some sort of test) and Daly had some extra cash in his pocket. However, there is no evidence to support the story, and the term was already in use before the alleged bet in 1791.

ID X.