[good night] {interj.}
1. Used as a polite phrase when you leave someone at night.
* /"Good night!" said Bob as he left Dick's house after the party. "I'll see you in the morning."/* /Bill said good night to his parents and went upstairs to bed./
2. or [good grief] — Used to show surprise and often some fear or anger.
* /Mr. Johnson's eyes opened wide when he saw the fish his little boy had caught, and said, "Good night!"/* /Mother was angry and said to Mary, "Good grief! Haven't you started the dishes yet?"/