Wiseguy Warning
It's when a mafioso, OG or gangsta puts a phonebook on someone's chest and fires a medium velocity handgun right against it. Thick phonebooks are known to stop .22, .45, and .38 bullets. It's common practice among goodfellas.
That guy got a Wiseguy Warning, he payed his dues not too long after. Rocco was ordered to give the guy a Wiseguy Warning.