THIS IS AN ANIME ONLY DISCUSSION POST. DO NOT DISCUSS THE MANGA BEYOND THIS EPISODE.
As the series progresses, Katte ni Kaizou gets better and better, somewhat becoming closer to what would be later called Zetsubou Sensei.
Anyway, my favorite part was Umi's childhood and Kumeta Kouji making fun of class-harem manga Mahou Sensei Negima. (Ironically, SHAFT has been animating the series recently and Kuemta later creates his own pseudo-harem manga called Zetsubou Sensei that become just as popular) :D
I liked this episode as well, but it took me some while to get over the eye color changes they made for this episode with no reason at all.
As for the Negima-Thing... The class in Zetsubou Sensei is defined to have 31 students, although we haven't seen them all yet. But the reason why it has that exact number of students is Negima I think. There's always been a kind of rivalry between Kumeta and Akamatsu.
You can see it in the beginning of the episode as well, which has a lot of references to Love Hina (and is of course taken from a chapter of the KK Manga)
So, I finally managed to get my hands on this episode and I can say that it didn't disappoint! It was less over the top apart from the banned games part and delivered its punchlines more subtlely which reflected on the calmer atmosphere of this episode.