The word that best describes this passage is satirical.
The passage is making fun of Professor Von Poddingcoft (or Puddinghead) and his reputation for being able to fall asleep during exams, which makes it easier for his students to pass. The tone is mocking and humorous, which is characteristic of satire. The passage is not meant to be taken seriously, but rather to point out the absurdity of the situation. Therefore, the word "satirical" is the most appropriate choice to describe this passage.