One of those lovely nonsense-sounding words. Maybe even a Mr T word. "I pity the foo' who tries the old acamarackus on me!" Or, "Mr T don't fall for that old ackamarackus!"
slang (orig. U.S.).
In phr. the old ackamarackus: a tale or explanation that seeks to convince through deception; a ‘tall’ story, a hackneyed tale; nonsense, malarkey.