Green’s Dictionary of Slang

(US) rubbish, trash.

1953		R. Chandler Long Good-Bye 149: I’ve written twelve best-sellers, and if I ever finish that stack of magoozlum on the desk there I may possibly have written thirteen.
1962		R. Chandler Raymond Chandler Speaking (1997) 200: There is a lot of magoozlum about blood splashes, but we end up with a very vague idea about how much and how far.
1994		A Roberts et al. Patchwork Girl of Oz 51: bo.: Load of malarkey. Codswallop. Poppycock. Magoozlum. Tosh, tripe, twaddle and tommy rot. ojo.: You mean it’s all nonsense.