The cabbage ( cavolo)is very used in our common sayings because as a vegetable,it is worth little ,so we give it a negative value.
quando qualcuno Si FA I CAVOLI PROPRI, vuol dire che he minds his own bussiness or in a more formal way SI FA I PROPRI AFFARI.
we have a headache and take a pill,but after an hour,the situation remains the same ,we can say'LA PASTIGLIA NON MI HA FATTO UN CAVOLO" (more formal"NON MI HA FATTO EFFETTO)
It means that we still have the headache :)
What Anna Maria said could be quite misleading as the following should be added:
1) these expression are far from common usage, although here in Rome they are welle understood
2) it is tolerated to use them IF the person has undergone a particular stress, for instance
the person got angry with the listener or has a need to emphasize a stressfull condition.
3) In other circumnstances (excluding jokes or in youngsters' talk) they could appear rather vulgar as there is just plenty of alternatives, so sticking to them could make the speaker appear as quite lazy in his or her speech and therfore disrespectful towards the listeners.
