It's likely to be a local pronunciation of Per piacere, which literally is “Please”, but may be used to exhort one to do something.

It's quite likely to be a local pronunciation of per piacere, which literally means “please”, but may be used to exhort one to do something.

As Charo remarks, the not-too-different Sicilian version pi piaciri is often found in Andrea Camilleri's books.