National Unfriend Day (17 November)

Invented by Jimmy Kimmel, American TV person, 2010...
"in an effort to remind everyone of the true meaning of friendship."
??
The idea was to go through the list of your "friends" on Facebook (or Wadeva) and "unfriend" all those who were not really friends.
"...any and everyone who does not add joy to your online, social networking experience."
??
(Sigh) I guess I should admit that the reason I am not a social media guy is that the first time I ever heard of Facebook, somebody explained to me that on Facebook, you make a list of all your friends. What a waste of time, I thought, and have never since been tempted.to join the millions. Likewise I have been strangely unmoved by the attractions of a service which would enable me to follow everything Donald Trump says every day, or to send all my friends a picture of what I had for lunch.
Now I guess I have no friends because I'm such an old grouch.
But about "unfriend":  It's an old word, says Crystal!
Well, yes, there is a word like that, from early Middle English, but it's a noun (= 'enemy'):
1275 We sollen slean houre onfrendes... (La3amon, Brut)
Probably survived to the 17th century, then was exhumed (by Walter Scott, of course) and used somewhat in the 19th.
Someone did, at least once, use that old word as a verb:
1659  I Hope, Sir, that we are not mutually Un-friended by this Difference which hath happened betwixt us. (T.Fuller)
But the modern verb is not attested before 2003. Crystal says "defriend" was a possible competitor for a while, but, no...