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...
I don't know about the 
shoulder dislocation part...
No entendí bien eso de la dislocación...
No entendí bien eso de la dislocación...
Não gostei desse 
ombro deslocado...