It's wrong to eat other people's food.
Jack and Diane are at a restaurant and both have a plate of French fries in front of them.
Jack wants to eat a french fry.
Jack grabs a fry off his own plate and eats it.
Jack reaches over to Diane's plate and grabs a french fry off her plate before eating it.
Diane watches Jack eat happily and continues to eat her own food.
Diane is angry that Jack is stealing her food and spreading his germs all over her plate.