I don't have the time tonight to think through my favorite religious or federal holiday. Generally, I like ones that don't celebrate colonialism or capitalism, and I especially like ones when they include intentionally making time for loved ones.
Anyway, the best frivolous holiday is on August 8th: Sneak Some Zucchini Onto Your Neighbor's Porch Night.
"Sneak" is already off to a strong start. Sneaking is fun. "Some" is nicely variable so that it can still be celebrated even if the harvest isn't great that year. "Zucchini" is a versatile crop that can be used in meals ranging from savory to sweet. "Onto your neighbor's porch" is remarkably covid conscious, introvert friendly, and makes the sneaking much easier in that it doesn't have to be inside or even interacting with anyone. Finally "Night" because it's the best time to go sneaking.
This holiday has been made worse primarily by the Amazon Subsidiary that makes Ring Cameras. I assume that anyone reading this post already knows many negative things about those companies, but also in the most practical sense, the rise of ring cameras makes it nearly impossible to sneak onto your neighbor's porch for any resson - even for a frivolous gift.