A day before yesterday. Finally, English language has a word for that.

See also, Fomorrow.
Come on, I wasn't born festerday! (i.e. I'm a bit slow, but not too much)

***

He's festerday's news. (i.e. he was yesterday's news yesterday)
by Seb Painter December 15, 2018
Get the Festerday mug.