Actually, this comes from a joke, the original text is as follows:

Lu Xun: "Good night!".

Chinese teacher: The word "late" in "Good Night" indicates the time,

it is reminiscent of the dark sky,

symbolizing the darkness of society at that time .

But under this dark sky, people feel "safe",

The side reflects the numbness of the people,

The exclamation point at the end of the sentence reflects Lu Xun's Insensitive to the people

"Sorrow for their misfortunes and get angry at them for not fighting."

Lu Xun: "Nah..."

Your Chinese teacher may have said it to liven up the atmosphere in the classroom, or it may have a special meaning.