Tsunade's Warning: Ninja No More!

is episode 98 of the original Naruto anime.

Synopsis
The episode starts with a Jonin whispering something to Iruka. He dismisses class, but hands out a homework sheet as well. The scene switches to Konohamaru, Udon and Moegi walking home. Moegi is glad that the class did not have to work on Taijutsu, and Konohamaru makes a remark. Then they see the Hokage's office. Two men are carrying the Third Hokage's things down. Konohamaru asks them what they are doing. They said they were moving the Third Hokage's things out so that the Fifth Hokage could move in. Konohamaru rushes up the stairs, and smells, as he calls it "A Lovely Fragrance." He then closes his eyes, and runs through he door, and smashes into Tsunade's breasts.

Tsunade calls Konohamaru "A perverted brat". After saying it a second time, she notices Shizune. Shizune takes Tsunade to the back room. Naruto runs into Konohamaru, and they crash to the ground. Naruto asks Konohamaru if he has seen "A big boobed young lady". Konohamaru replies no. Tsunade goes to the hospital, to heal Sasuke Uchiha, Rock Lee and Kakashi Hatake. When she heals Sasuke, Sakura hugs him tightly, while Sasuke is emotionless. When Naruto leaves, Tsunade notes what a compassionate kid Naruto is. She heals Kakashi. When she heals Lee, she says some injuries are embedded deep in his Spinal Cord, so he can't carry out Ninja tasks. So, she tells Lee to give up being a shinobi. Lee walks down the hallway, sobbing.

Trivia

 * The segment in which Konohamaru rubs his face in Tsunade's breasts is removed in the English dub.
 * The bulk of this episode does not occur in the manga.