Maybe the Gibbins Weidenhagen Gambit?
It's at least fun to say ![]()
This might not be long, but if you play this regularly your tongue will want to strangle itself.
Delayed Exchange Ruy Lopez Deferred.
Slav Defense: Modern, Alapin Variation, Czech, Krause, Wiesbaden, Sharp Line, 8...Bxe4 9.fxe4 Nxe4 10.Bd2 Qxd4 11.Nxe4 Qxe4+ 12.Qe2 Bxd2+ 13.Kxd2 Qd5+ 14.Kc2 Na6 15.Nxc4 O-O
Nimzowitsch Defense: Scandinavian Variation. Bogoljubow Variation Heinola-Deppe Gambit
1.e4 Nc6 2.d4 d5 3.Nc3 e5
This is the longest i have heard of giuoco piano game: giuoco pianissimo, italian four knights canal variation