It's not my creation as it's been around since at least the late '80s when I read about it in GAMES Magazine, which, back then, had a schedule of events section each issue which often included at least one of these sorts of days. Including April 31st as Diacritical Day.

According to the blurb in the magazine, You're Welcomegiving was primarily invented so those who've overindulged in turkey and blood sports – er, football, that is – can have a four-day weekend, thus allowing the wives to use them as pack mules in the stores.