In his book "The Ruy Lopez Revisited", Sokolov referred to it as a fully-fledged variation.

Liviu Dieter Nisipeanu surprised world's number one Magnus Carlsen last Thursday, by choosing this gambit to equalize easily in the ninth round of the Kings Tournament.

You might have guessed it by now, I'm talking about the dynamic Jaenisch Gambit. Proven sound to play against Carlsen, it should certainly be safe for you to use!

"The Jaenisch should appeal to any black player who's 'looking for trouble' at an early stage of the game. I personally support Black's cause." - Ivan Sokolov

Imagine your opponent's face when you play 3...f5 in the Ruy Lopez yourself!