"Nicknames" (あだ名, Adana) is chapter 311 of the original Naruto manga.
Sai visits the library to learn about how to make friends. After reading about nicknames, Sai tries to put the concept into practice by calling Sakura "ugly". He and Naruto, who tries to keep Sakura at bay, are injured in her wrath. The three meet with Kakashi in the hospital and tell them about their encounter with Sasuke. Because Sasuke has become so much stronger than them, Naruto worries that they will only fail again the next time they try to retrieve him. Kakashi replies that Naruto will merely need to get stronger, and proposes a training method that only Naruto can undertake.