Only a baby’s yawn is sincere, that of an adult signals a desire for food.
Yawning is mostly involuntary, and sometimes serves a social function such as communicating boredom. The proverb can be translated as,’ A genuine yawn is that of a child, that of an adult signals a desire for food.’
Some actions or statements shouldn’t be taken as they are. Sometimes people use an indirect approach to communicate or ask for what they want.