I didn't think there was a need to explain an episode like this other than. "...WTF"
Triple R and a few others are right - Just because some people don't like a particular element, character, episode, etc., there's no need to try and 'convert' them, persay or even try to explain it to them (unless they ask for it). They understand what happened - they watched the same episode we all did.
We all just picked up different things from it.
And no, I'm not aiming a mallet at anyone, just my $0.02
The only real thing I got from this episode, other than not-so-good ideas about toothbrushes, was that Koyomi and Karen have reached an entirely different plateau of awareness for each other thanks to this. I got my own expounding theories on why it happened, why Koyomi chose a toothbrush of all things, and why Karen got what Nadeko tried so hard to get (
), but I don't feel like writing all of it right now.
If anyone wants to compare 'theories' that's fine by me - would be interesting to read what other's picked up on at the very least.
...maybe I will go read at least this chapter in the novel to see what I'm missing out on.