The account at Genesis 21:9 speaks of Hagar’s son IshmaEl ‘playfully making fun of’’ Sarah’s son IsaAc.
The Greek word that we have used to translate this phrase is paizonta, which refers to child’s play or a sporting activity or game. However, the root comes from the Greek word empaizo, which also means to deride or make fun of, or even to get too familiar. As the result, we have concluded (from Sarah’s reaction) that some sort of disrespectful act was implied in the play. Notice that the same word is also used to describe IsaAc’s actions with his wife Rebecca (at Genesis 26:8), which caused King AbiMelech, the king of GeraRa, to recognize that she was IsaAc’s wife, not his sister.