Not that recondite a word, but any soupçon from the Magister is welcome here:
I just want to say, publicly, and despite the possibility of offending some friends, that I thought the fake death gag puerile and unhelpful.
1. Immature, especially in being silly or trivial; childish.
2. Archaic Belonging to childhood; juvenile.
Notice that the second definition is archaic. Literally, the word means “of a child”; in a legalistic sense, I suppose that encompasses teens. Not all that children do, though, is childish; and not all that adults do is mature.
And yes, some things that children do are childish.