Recently the birthday tag has emerged and it quickly has around 100 questions tagged (mainly by one user I suppose).
My concern is probably naive since my understanding in probability/combinatorics are minimal: Is the term "birthday" commonly used? That is, is there a somewhat well-defined sets of questions where people will instinctively add "birthday" as a tag, just like what people do for, e.g. the tag "probability", "combinatorics"?
The term just sounds too layman to me.