Surprise Attack! Naruto's Secret Weapon!

is episode 45 of the original Naruto anime.

Synopsis
Using Kiba's own smokescreen as a cover, Naruto disguises himself as a third Kiba through use of the Transformation Technique and tricks Kiba into knocking Akamaru out, which only serves to anger Kiba. Naruto, however, is still at a disadvantage due to Kiba's pill-enhanced chakra and superior speed. Kiba's onslaught ends when Naruto accidentally farts in Kiba's face due to straining himself too hard, resulting in a disastrous effect on him due to his enhanced sense of smell. Naruto then finishes the battle with Naruto Uzumaki Combo, a technique he based off of Sasuke's winning move that utilises his shadow clones.

¡Ataque sorpresa! ¡El arma secreta de Naruto