Episode 4 was only really good for introducing Popo. The Snake jokes fell kinda flat, and, if I remember correctly, the Pac-Man scene was pretty bad.
It might still have received too low of a rating; it had to be better than the first three episodes, at least. Or maybe the first three had ratings that were too high. I know for a fact that jokes about George Bush and Myspace were enough to stop me from watching the series until I decided to give it a chance years later.
Also, tagging this.
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xfd dude, it's just a popularity contest on the internets.
-Vlado