3x13 - Sayonara Zetsubou Sensei

When Chiri hangs up a painting upside down without noticing, the class are taken through a gallery where involving big mistakes that go unnoticed compared to the minor details. In the second part, Nozomu accidentally causes Kiri's blanket to fly away, and the class go on a search for it. However, it flies onto a government member who decides to mass produce it so people will feel more secure. Soon everyone decides to become civil servants and the world becomes impoverished. In the third part, Nozomu and company discuss buzzword generals and are disturbed by one. Maria then mentions "Kiyohiko's Night" (a mispronunciation of Silent Night) and a Kiyohiko shows up, but is unprepared for the abrupt pun.