Do you remember the Japanese Fanta CMs where various extravagant teachers showed up in a class and held a strange lesson? Somebody took the audio from those CMs and inserted it into scenes from K-ON!!, Angel Beats!, and Working!. Particularly the K-ON! video is quite well done but all the three are very funny.
Original Fanta CMs: K-ON!! version Working! version Angel Beats! version
Original Fanta CMs:
Angel Beats! version