The Telltale Moozadell - S3-E9
Continuity mistake: During the scene where Rocco gets water thrown at his face, the position of his hands differs between the close-up and the wide angle.
The Telltale Moozadell - S3-E9
Visible crew/equipment: After their school meeting about AJ, while Tony and Carmela walk outside talking about AJ's lack of punishment, as the camera moves backwards, the camera's dolly track is visible at the right side of the screen.
Answer: It's a mafia thing. Taking food off another made man's plate in public view like that is comparable to the guy in Casino taking off his boots and putting his smelly feet up on the table.
It is not a "mafia" thing, it's basic manners and plain gross for another person to stick their fingers into a plate of your own food. Same with the feet on the gaming table scene in Casino. It's not a "mafia" thing, it's just rude and not something a person does in public.