It is said that in the upper reaches of the Yellow River, it is difficult to sail. For this reason, local people often use rafts made of cattle and sheepskin to cross the river. It is made up of several cowhide bags shaped like bags. When using it, the raft is blown up with their mouths, so the word "bragging" came into being at that time. You can't blow a raft without enough strength and empty talk. People often say to people who talk empty words: if you have the ability, go to the river to brag. Since then, people have called those who have neither knowledge nor working ability, love to talk empty words and exaggerate things "bragging"