Yeah I'm generally a big fan but that one is a bit obscure - according to this [0], it's just the incongruity of trained professionals in mortal danger using a childish nickname for the thing that's about to destroy them.
I think it's simply out of fashion. E.g., "Don't mess with Mr. In-between" is a line from the 1940's song "Ac-Cent-Tchu-Ate the Positive." It's addressing abstract entities in a personalized form, which --I assume-- is a style convention commonly understood at the time.
