Deletion of Opposite Day (2nd nomination)

Comment: Upon glancing at this AFD my first instinct was to write "keep per the new sources". However having now looked at these sources, I don't feel it would be right to do so. Am I missing something obvious, or do none of the sources being cited above provide any actual ''information'' about Opposite Day? The google news hits (at least, those that I can find) don't appear to discuss "Opposite Day" at all in this context, while most of the remaining sources above, while they use the term "Opposite Day", they don't cover the phenomenon in any detail and simply use it as a descriptive term or to introduce a philosophical concept. For example, the article begins with "''Opposite Day is a fictional holiday which is celebrated by many schoolchildren''" - but none of the sources cited so far, that I can see, contain anything that supports this. Basically the only information we have from the sources is a brief definition and I fear that unless we find an article actually covering Opposite Day as a "fictional holiday celebrated by many schoolchildren", rather than a philosophical term or a term used to introduce an exercise, we risk ending up with an article that is just full of . I'll hold back my !vote for now while I try to find some more informative sources and take a closer look through those cited above in case I'm missing something glaringly obvious
Stance: comment
Cited policy: Wikipedia:No original research (WP:OR)