This is the 19th post in a daily series. Read about it here and see the list of previous posts here. A new post about “Star Wars” will be posted every day for 40 days leading up to the franchise’s 40th birthday on May 25th.

In a 2014 episode of “The Big Bang Theory,” the gang feverishly prepared to celebrate Star Wars Day, a day to celebrate all things relating to the “Star Wars” universe. The holiday fell on May 4, because there’s a built-in pun: “May the Fourth be with you.”

By the time this episode aired in 2014, Star Wars Day had been a well-known quantity, at least among fans of the franchise.

But the pun that dictates the holiday’s place on the calendar – “May the Fourth be with you” – is about as old as the franchise itself. In 1979, Britain’s Conservative Party celebrated the election of Prime Minister Margaret Thatcher by taking out a full-page ad in the London Evening News, which read, “May the Fourth Be With You, Maggie. Congratulations.”

The pun has appeared in British politics again at least twice since then: once, in a 1994 House of Commons discussion, and in 2012, when London Mayor Boris Johnson mentioned the phrase in his acceptance speech after being re-elected.

By then, there had already been at least one organized Star Wars Day celebration. The Toronto Underground Cinema had first hosted an event in 2011.

But the mainstream acceptance of Star Wars Day as a holiday — or at least a gimmick — seems to have come after Disney purchased Lucasfilm and the rights to “Star Wars.” Since then, the company has taken advantage of the holiday (and the fans who celebrate it: Star Wars Day includes deals and discounts on “Star Wars” merchandise, as well as events at both Disneyland and Walt Disney World. The day also provides other companies the chance to market themselves to “Star Wars” fans.

And even the crew of the International Space Station celebrated Star Wars Day in 2015, watching “Revenge of the Sith.” In space.

One could be tempted to say this holiday was a shameless ploy that takes advantage of nerds. That’s a fair assessment. But then again, George Lucas and Lucasfilm have been taking money from nerds for 40 years. And we’ve been happy to let it happen.

Sign up for the weekly newsletter here.
Follow us on Twitter and Facebook.