What does the girl mean by "ha ha mirror"?

"Girls say ha ha mirror" means: very funny, like a clown.

My deskmate thought of this topic:

The deskmate is a humorous person who likes to talk about relationships. However, if you listen carefully, you can hear the meaning of this sentence.

There is a boy in the class who is very naughty. He always jumps up and down every day and always causes all kinds of troubles to others. He is a very annoying type. Later, this boy often teased my deskmate and said something inexplicable. Then, the deskmate said, "You are a mirror." This means that you are a clown. That's hilarious.

Yes, everyone has his own way of doing things and different personalities, but you should learn to restrain yourself and become a respected person, otherwise there will be fewer and fewer friends around you.