As the corresponding opening already is in this great, a bit 'messy' style the ending takes after it. Maximum the Hormone gives the ED its powerfulness and Raito even provides some fanservice, who would've guessed that?
And an elevator, how cool is that? :D
First I found it kind of weird but then I loved it. The animation style is great and once you hear the song a second or third time it gets really cool. ;)
Although when only seeing the ED one wouldn't neccessarily associate it with Seitokai Yakuindomo at all.
Somehow the ending is addictive as hell. I always watched it because I wanted to know which character came next and after I knew it I still watched it again next episode.
It's a great idea and I also like the little photo-like snippets of Ikebukuro in the beginning.
Hare Hare Yukai
It's such a classic, how could I not love it. Especially after learning that dance (which unfortunately I have forgotten by now :C). I also love Koizumi's elation in the dance. He's too great for this world...but I'm getting off the point. ;)
SM Hantei Forum
The ending that is sung by Kagerou aka Tomokazu Sugita is as absurd as the character. And that what makes it so brilliant. Not only that Sugita's voice isn't lovely enough, the lyrics are...so stupid that they are good again. The animation is nice and the song is catchy.