The Hostile Hospital: Part Two - S2-E8
Trivia: When Olaf catches Klaus in the corridor while Klaus and Sunny are disguised as a doctor, he tells Klaus that he looks terribly young to be a doctor. This is a reference to the fact that Neil Patrick Harris, who plays Count Olaf, played the role of Doogie Howser, a teenage doctor, in "Doogie Howser: MD" in the late 80s to early 90s.