Stew : noun (word from Italian decoration meaning " seasoning ").
The way to do cook some meat stifled in a container closed.
Turnip, failed film.
Object, realization of poor quality.
It's crap! : it's worthless.
The expression "It's crap!" »: It is an object or a spectacle of poor quality, good to throw away.
Le stew here is a slang word used in connection with a worthless thing or person. It is attested as early as 1881 to first designate a "kitchen slut", but nothing seems to indicate the origin of this substantive.
But so that you do not remain hungry, we can still specify that, according to Gaston Esnault in his Dictionary of slangs, daube would be here a word of Lyon origin to say "spoiled", applied to fruits and meats, which could very well explain the origin.