http://www.potsaa.com/bread-butter/

If someone made pasta is it OK to eat a piece of buttered bread with it? Or bread with peanut butter?
If someone you made a pasta dinner is it rude to add bread? What is it that the bread and butter? What is it that the bread and peanut butter?
If there is no bread and butter / peanut butter? I do not ask if I was trying to be polite. If it's more of a casual date I would not find it offensive. Who eats bread peanut butter with pasta, right? It may be rude just to ruin the other persons appetite.
The Newbeats – Bread and Butter (1964)