I believe that Yermolinsky actually used this term somewhere in his own book.
After reading the book of Ulf Andersson’s games “Grandmaster Chess Strategy”, I took a page from it when I played this game on FICS. Secret-sauce tip alert! I consider my opponent’s defense to be the best practical one against the King’s Gambit accepted. First, my opponent “fakes” the Cunningham variation with …Be7, and then plays …Nf6 on the very next move.
Surely, my opponent has taken some pride or satisfaction in his opening play, and can see a well-played draw in the near distant future, but he probably doesn’t know about Ulf!
Ulf Anderson would gain space, trade pieces, and win by zugzwang. Okay, so my opponent just gave me a pawn en gratis, but often an opponent might do this just to make you prove that it isn’t a draw!
Believe it or not, after 25….b5?? (…b6 is better), my opponent is lost.