"Humbug" was the eighteenth-century analog of "bullshit". When Scrooge says "Christmas? Bah, humbug!", he's effectively saying "Christmas is bullshit, man."
Scrooge was hardcore.
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I think that one defines themself through reinvention. To not be like your parents. To not be like your friends. To not be like your peers. To be yourself. To carve yourself out of wood.