Sasuke noticed right away that something was coming.
First day Naruto apparently struggled with something. Sasuke pretended he didn't see anything.
Second day Naruto kept peeking at him. Sasuke didn't react.
Third day Naruto suggested, "Let's play rock-paper-scissors." Sasuke raised his brow, Naruto went on, "If I win, you'll get to kiss me." Sasuke raised the other brow, contemplating Naruto's blush. "If I lose, you'll get to beat me." Sasuke nodded in agreement.
It ended in a draw.
Sasuke curved his lips, snorting; Naruto looked sadder.
Sasuke's smile grew warmer as he leaned towards Naruto.
After a moment of sweetness and softness, Sasuke put, "I too always wanted to find out how it would feel when done properly."