Blame Kishimoto for giving Haku a tool-complex, it's what inspired this.
Naruto looked upon the defeated ninja, not understanding how someone could lose the will to live after one single defeat. His whole life had been a succession of failures and he never gave up, the very concept was foreign to him, so he couldn't understand why Haku had just stopped fighting.
"Why Haku? Why are you so ready to die?"
"Because I failed Zabuza-sama. I am but a tool … a toy."
"A … Toy?" Asked Naruto fearfully. He may be a bit dense but he was not naïve. He knew what it could mean.
"Yes … A toy."
Haku moaned in delight as her hips moved relentlessly, grinding against her master's in a dance of lust and passion.
"Z-Zabuza-sama!" She gasped after a particularly hard thrust. Her hands travelled along his skin, caressing everything they could reach ,touching every bit of taut muscle, sensually dancing across the sweat-covered skin. "I-it's so good!"
"Less talking." Grunted Zabuza, slamming hard against her hips, making Haku gasp again. "More fucking."
"Ah, Z-zabuza-sama, i-it's coming! It's coming!" Screamed Haku at the top of her lungs as she buried the length of pink plastic in Zabuza, causing the mighty swordsman to erupt with a grunt.
Haku looked at the sky with stars in her eyes and a wide, happy smile; her hands clasped together, the fingers intertwined. Naruto looked green, Tazuna had eyes the size of saucers, Sakura had a wide and perverted smile and blood flowing from her nose, Zabuza was paralyzed by large and shocked dogs and was red as an apple, and Kakashi was stopped mid-chidori.
"Wow, Zabuza," He said conversationally. "Wouldn't have guessed you …"
"Shut up." Interrupted Zabuza. "Just … Shut up."
Ha! You didn't see that one coming, did you?