In this paper, frogs need to use exclamation marks to express their feelings when writing poems, but they don't use punctuation marks. So in frog's poems, if you need an exclamation point, you will use croak instead. For example, in Quack, Quack, Quack! In this sentence, "quack" is the cry of a frog, which is used to express the emotion of exclamation.
So when a frog writes a poem, if there is an exclamation point, he can use the frog's cry "gung" as it.