It's polite to wish people a good night.
Josh lives at home with his parents.
Josh just got home from work and wants to go to bed.
Josh tells his parents he's tried from working and wishes them a good night before going to bed.
Josh walks past his parents on his way to his room without saying a word.
His parents give him a good night hug and all three are happy.
His parents are upset that Josh didn't acknowledge them.