不要轻易承诺 Don't promise easily

河马对孩子说：人们总说河马嘴巴大，但是大嘴不是为了轻易作承诺，而是要大声说“不！”

The hippo said to the children: People always say that the hippo has a big mouth, but the big mouth is not for the sake of easy commitment, but to say "no!"