Hi, 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.

È in dialetto. .

it's like a insult connu= is man with wife libertine lass stare amica mia= Stop , Don't annoy my friend it's a sicilian dialect

hi henrik, federico gave a good answer; to be more specific: it's clearly a dialecto from south, very probably from sicily; a literal translation could sound like this: "are you fool or do you eat grass? want you to leave alone this (girl) friend of mine?" the word 'cunnu' specifically referres to the genital part and in this case is used in a very offensive way; eating grass is typical of animals (mules, horses, cows etc.) so you can easily understand that is offensive too take care