Not OP but wouldn’t be surprised if it was around the Med... in Italy there is a kids’ saying that goes “a spy is not a child of Mary” (“chi fa la spia non è figlio di Maria”), i.e. grasses are going to hell.

The south of Italy is entirely corrupted by organized crime, so I'm not sure it's a very good example.

Hadn't thought of it, but given Catholic schools and area, so probably similar. Early christians met in the catacombs of Rome, so the tradition of keeping it between you and your priest (sub rosa) might relate to the culture. Their whole mythology is about the consequences of betrayal to political authorities.

I wonder if there is a link between these snitch cultures and secularism/atheism. Rather puts a spin on "keeping it G," as well.

I had a teacher who was a WWII Holocaust survivor.

One day a kid tattled about something and the teacher roared "Don't snitch!"