What is, "the narwhal bacons at midnight" equivalent for Lemmy?

Please excuse my ignorance, but what is “the narwhal bacons at midnight”?

Reddit folklore.

In the times when it felt like a small community, someone was in an airport, I think and thought another person was on Reddit. They asked how they could tell for sure, and it was decided there should be a question someone could ask, where the answer would make it clear that they were a Reddit user. The question was “when does a narwhal bacon”. The answer was midnight.