Three writers have writing credits on “The Strike”: Alec Berg, Jeff Schaffer, and Dan O’Keefe (via IMDb). In an interview with Uproxx, all three shed light on the inspirations for the episode.
Obviously, there’s no such thing as a real-life Human Fund. The whole joke is that it’s a fake charity that only exists to give George an excuse not to give gifts. Berg was inspired by “Seinfeld” production company Castle Rock’s tradition of giving holiday gifts to employees. During the “Seinfeld” days, Castle Rock would give out cards saying that a donation had been made in their name to a charity. “We always wondered how much they had donated, and if it was made in our name, why couldn’t we use the tax write-off?” Berg explains.
The gifts weren’t very popular. Eventually, the writers realized that an unscrupulous person, like George, could simply give out cards claiming that donations had been made to charity, without actually giving money. The writers decided the charity needed to have such a vague sounding name that nobody would question it. They landed on “The Human Fund.”
Festivus, on the other hand, is very much real. O’Keefe’s family celebrated a similar anti-holiday during his childhood. He claims he was so traumatized by the memories that he was reluctant to include it in the show. Luckily for American pop culture, Berg and Schaffer overruled him.