SKET Dance Season 1 Episode 27 E 27

The Sket-dan get a new assistant homeroom teacher (who wants everyone to call her, Onee-san), but she's a klutz and is upset she can't be a good role model for the students, so the Sket-dan ask Chuu-san to help with some of his strange drugs. Later, Switch goes through some old inventions of his that didn't work out as intended...