It is indeed a thing, you'll be interested to learn, or at least a meme of about 3 years's standing. The Wikipedia article was created in 2023.
https://en.wikipedia.org/wiki/Brown_Friday
It's interesting how it has (and has not) spread to non-U.S.A. parts of the FediVerse.
If memory serves (I've since deleted it off the TiVo.), it was on this week's episode of QI. So it might do the rounds in the U.K. a bit more, this year.
Out of curiosity, I just checked.
The place to go on the #FediVerse for #BrownFriday plumber posts is Mastodon.Social.
Both MastodonApp.UK and Mastodon.Scot have had the hashtag since 2023, but only MastodonApp.UK has pulled the Mastodon.Social posts.
Toot.Wales, SFBA.Social, Mstdn.Social, and Mstdn.CA all have the same 1 BlueSky #BrownFriday post, from yesterday; and Mastodon.London and Glasgow.Social have not yet had any posts with that hashtag at all.
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