I expecially liked Kuroi Sensei' performance ^^
that part where thinks about going to sleep early and getting old... oh my, I feel the same...
about the "chin chin" gag... I'll tell you a funny trivia ^^
If by any chance you hear italian people saying that in Japan, they probably don't mean to be obscene... because in italian language, "chin chin" means cheers, kanpai!
