c933103 said:
Would it be a good idea to create a new tag that would act as a parent for pocky_day cat_day twintails_day kiss_day meat_day and other countless days? How should such tag be named?
Why would such a tag be needed, though?
Some catchall tags, like food, are necessary because you often can't tell what, exactly, something is supposed to be. I have no idea what the girl in post #2996144 is supposed to be eating, so a more specific tag would be inappropriate. We need a purposefully vague tag because it's often the only tag that applies to a given object.
For images that reference specific days, this is hardly the case. These images focus so heavily on particular themes that there is little doubt about how they should be tagged. If there are any posts referencing days that aren't currently tagged, it would make more sense to create tags for those days specifically rather than create a much broader tag that doesn't appreciably help narrow search results.
If, for whatever reason, you really want to search for multiple such days at once, you can use a multi-tag search like ~pocky_day ~cat_day ~twintails_day ~kiss_day ~meat_day, and so on. If what you're actually looking for is a list that includes similar date puns and commemorative dates, try Tag Group:Holidays and Celebrations.