I was in a restaurant in Vancouver and a man did not finish his breakfast and asked another diner (who appeared to be a stranger) if he wanted to finish his meal,the guy said yes and was handed the plate he scrapped the hash browns off the plate and ate the toast.At first that appeared very strange to me but after thinking about it remembered that in the 50s and 60s that was not all that unusual.To offer someone (a stranger) an uneaten item off your plate.Or when flying perhaps offering the person next to you an uneaten item off your tray.