What do you mean by leaning forward and leaning back?

Leaning forward and leaning back means to describe the body shaking back and forth (especially when laughing).

Tilt forward and backward [qiá nf ǔ há uyng]1. Bend forward and lift back. For example, "This joke is so funny that everyone laughs their heads off." Idiom (pinyin: chéngyǔ, English: idiom) is a stereotype in Chinese vocabulary. Idioms, everyone says they have become words, and so do idioms. Idioms are mostly four-character, and some are three-character, five-character or even more than seven-character.

Idiom is a major feature of traditional culture in China, which has a fixed structure and a fixed sentence, indicating a certain meaning. It is applied to a sentence as a whole, with subject, object, attribute and other components. A large part of idioms are passed down from ancient times and represent a story or allusion.

Some idioms are just a miniature sentence. Idiom is a ready-made word, similar to idioms and proverbs, but slightly different. Idioms are a bright pearl in China culture.