What do common words mean?

"Climbing the ashes", also called "picking up ashes", has the same meaning: it means that the father-in-law commits adultery with his daughter-in-law. Then why is it called "climbing ash", not some other word? What are the allusions here?

Before the formal lecture, tell a little joke. That was when the educated youth just jumped the queue in the countryside. It's the turn of two male educated youths to cook lunch. When they grabbed rice and added water to make a fire, they found that there was too much ash in the stove, so they couldn't cook without cleaning it up, and they didn't have tools, so Xiao Z, an educated youth, quickly borrowed it from his neighbor. The local villagers have simple folk customs and are very willing to help the educated youth. Coincidentally, the one borrowed by the educated youth happened to be the new wife at home. The educated youth greeted him and said, "I asked you to borrow a cleaner." Unexpectedly, the woman blushed and didn't say "borrow" or "don't borrow". She just kept saying, "What? What? " Little Z thought he didn't hear clearly at first, so he repeated it loudly. Unexpectedly, the woman is still "what, what?" Now Xiao Z thought she didn't understand, so she made a gesture to explain, but the woman did it anyway. This makes Xiao Z wonder: the relationship is good at ordinary times, and it is very refreshing to borrow some tools. Why is it so difficult to borrow a duster today? While speaking, the neighbors gathered around and asked what was going on. When Xiao Z said it, everyone laughed. A woman picked up a tool to dig out the ash and said to little Z, "Is this it?" When Xiao Z saw it, it was of course good. He even said, "Good, good, thank you." The woman taught him, "this is' scraping' ash, and it can't be called' scraping' ash. \ picking up ashes \ is a dirty word, so you can' t say that \ college students \ (commonly called educated youth college students by locals) don' t even understand this, can you? " This made Xiao Z blush. Whether it was "picking up ash" or "digging ash", he quickly took it back to dig ash for lunch. At lunch, everyone talked about it. Some students with a wide range of knowledge explained that it might be misunderstood as "crawling ash". At this time, Xiao Z understood and thought: It is really lucky to ask the new wife what to borrow to "pick ash" and flirt with women without wearing a hat. This is not Xiao Z's worry. In that era when class struggle was the key link, anything could happen.

Then again, even so, the educated youth has not solved the mystery of why the adultery between the father-in-law and the daughter-in-law is called "climbing the ashes". It turns out that there is an allusion here, which comes from Mr. Su Dongpo, a great writer. It is said that Su Dongpo lost his wife in middle age and never married. He was busy with business and writing for many years, and soon his son got married and had children. It happened that Su Dongpo's generation was brilliant, brilliant and brilliant, while his son did nothing but eat, drink and be merry all day. One day, Su Dongpo's son went out to play again. Su Dongpo sat alone in his study, thinking dully about this problem. At this time, his daughter-in-law saw her father-in-law brooding in the study and brought him a cup of tea. The daughter-in-law, wearing a white gauze skirt as transparent as a cicada, walked up to Su Dongpo with a teacup and whispered, "Dad, please have tea!" "And looked at him affectionately. This daughter-in-law is actually a talented woman who knows everything about piano, chess, calligraphy, painting, poetry and songs. The reason why she married Su Jia was the worship of Su Dongpo. Only after he came did he find that his son was so mediocre. He was lonely and disappointed. I have long admired Su Dongpo, and I want to be close to my father-in-law today.

Su Dongpo was deep in thought when he saw his daughter-in-law. After a while, his eyes looked at her. His daughter-in-law's red face, graceful figure and affectionate eyes suddenly got carried away. Just when he was in high spirits, he suddenly remembered that this was his daughter-in-law blushing at once. Daughter-in-law asks: "Why does father-in-law blush?"

Su Dongpo did not answer. He picked up the teacup and quickly wrote two poems on the table with his index finger: "There is a pipa in the green gauze tent, which can't be played even in spring." Because Su Dongpo was lazy and didn't clean the table for a long time, there was a thick layer of ash on the desktop, and the handwriting was very clear.

After reading it, the daughter-in-law quickly wrote two more sentences with her fingers: "If the father-in-law plays a song, the fat water will not flow to outsiders." After writing, I ran away with a red face.

Su Dongpo gloated when his son came back. Seeing his father so happy, he asked, "Father, what are you looking at?"

Su Dongpo got a fright. He quickly wiped the handwriting on the table with his sleeve and said, "I don't see anything. I'm scraping the dust."

In fact, Su Dongpo has four sons. Except the youngest one is dead, the other three are all ok, especially the third one, which is very successful. The above legend may have been deliberately arranged out of jealousy. In fact, according to Tian Yu's research, the origin of "crawling on the ash" is that if you climb on the ash, your knees will definitely be dirty, that is, your knees will be dirty, and its homonym is "dirty daughter-in-law". In Chinese, you don't usually say "dirty daughter-in-law" and like to turn a corner, so "dirty daughter-in-law" is "crawling on the ash".