doing
something subjectively meaningless, i.e. something that is objectively useful to everyone, including yourself, except the
person who uses this phrase on you, who defines your activity as
useless and subjective only to themselves).
mother: Adam, go help your
father in the yard, if I may interrupt you. All you've been doing to
day in playing Minecraft.
Adam: okay, I'll go help dad, but remember that the purpose, of playing Minecraft, I mean the actual
game, is subjectively meaningless to youm, since everybody objectively defines it as useful except for you. (Adam goes off to help his dad).