piespy: I sense converse fallacy. p -> q doesn't mean ~p -> ~q. I.e. you can conclude from "cogito ergo sum" that if X doesn't exist, then it doesn't think, but not that if X doesn't think, then it doesn't exist.
To further back up 0xCCBA696, let us assume that thinking automatically implies existence, and not thinking does not imply existence nor non-existence. Thus, given that you, clearly, were not thinking when you wrote that post, we have no way of knowing if YOU exist or not.
Honestly I expected the joke to be about Kamigishi Akari, since their similarity is even referenced in the show. But Akari has red hair so I'm not changing anything.
as others have pointed out: there's some interesting implications to the fact that Kikyou is clearly worried about Kasuza eating the cake + Serika eating pre-packaged food instead of the cake... did Kayoko lace it with something (or, at the very least, do they think she did)?