Sasuke knows that he and Naruto are total opposites in many ways, from their looks to their personality and to their favorite food. He expected drinking to be one of them too. Because while Sasuke can hold his liquor pretty well, he thought Naruto would be the complete opposite. This is not the case, however, as Naruto proves by outdrinking everyone. Sasuke is forced to realize that just because Naruto is not an obnoxious drunk does not mean he is different from the sober Naruto, and that there are a lot of hurt feelings under the surface. He supposes it's his turn to do the comforting. Or: Konoha 12 is drunk. Sasuke is trying his best not to kill the villagers. And Naruto just wants to sleep because being drunk means dealing with emotions that he likes to pretend does not exist.