Bulletin Boards Do Still Exist
No, this does not involve that site.
I think there's still a real life bulletin board in just about every grocery store. Since you'll probably go to a grocery store today, find something you can pin to the board and celebrate Pin Something onto a Bulletin Board Day.
Obviously what you pin doesn't have to be an actual notice that someone will want to read. You can pin that stray sock that never has a match once it comes out of the dryer.
You can pin a blank piece of paper. That one might be interesting to watch later to see if people think there really should be something printed on it.
Living things probably shouldn't be pinned to the board.
You can pin a piece of produce there. (Remember, you're in a grocery store, so that's easy to find.) That one also could be interesting to watch.
You can blow up a balloon and pin it there by its stem. Another good one to watch.
Maybe this day should be renamed to Watch Something You Pinned onto a Bulletin Board Day.