A number pun based on a particular date. Many of these dates are celebrated by artists posting art designed around a certain theme. This tag should be used if the art itself references the date pun in question.
November is notorious for having a lot of these because "11" resembles イイ (good/great). For example, November 29th is "good meat day" (ii niku no hi) because two (ni) and nine (ku) sounds like meat (niku).
