Is there more context? All I can imagine is that "midnight" is used metaphorically to indicate some imminent disaster (like the Doomsday Clock) and that the group who is supposed to be addressing the problem is making jokes instead of getting down to work.
Or it could just be that they're working very late into the night and the speaker is irritated that the work is being interrupted by kidding around and laughing, as the hour grows even later.
[native speaker & writer, not a teacher]
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