This episode had some truly brilliant moments but the first 1/3 wasn't so great. It was kind of slow and not so funny. Butters being injured was more disturning than funny. The song is a riot and this has some trivia: http://en.wikipedia.org/wiki/Good_Times_with_Weapons
The word "Let's" is very often abused in Asian culture. In fact there was a new wave group from England or America called "Let's Active" which was named after a silly sign they saw in Japan.
What real anime shows are like the parody scenes? One might be Street Fighter.
I also thought Chinpokomon was a good satire but it wasn't a great episode overall.