To describe a person as feeding an unfamiliar dog, it means that no matter a dog or a human, you cannot give too much, otherwise he will take it for granted, and you should treat him like this.
A dog is most loyal to its owner by nature. No matter how good it is to the bones or meat that others throw to it, It was unmoved. Even after it was gluttonous, it would never look after someone else's home or yard and would not obey orders. It still thought about its original owner. 'Feeding an unfamiliar dog' is a metaphor for someone who is ungrateful and ungrateful, and refuses to acknowledge or accept his kindness no matter how good he is to him. 'Eating his father and drinking his father without thanking his father' means wasting his good intentions towards him and even 'calling him brother to his face'. Pulling out a knife from behind and turning against him ruthlessly! Ruthless, righteous, shameless, and without mercy or kindness. What a villain and coward!
