ok, these phrase came from a Italian dialect language. Each region of Italy has a native dialect that is quite different from Italian language. It is a "sub-language" that you can find in each different region of Italy.
However, the second phrase : "lass stare l'amica mia" mean "do not annoy my friend" when someone tries to flirt with a girl and she does not like the situation, thus a friend of her tries to send away the guy with this phrase. After if the guy continue to flirt, probably the guy is in a big trouble :).
The first phrase means " are you stupid?" but it is an Italian dialect language.