请用英文介绍一下下面这段话，写出段落大意。
写作思路：根据题目要求，以其中一个句式作开头，编写一个小故事，编写的时候，要生动。
正文：
Long long ago,there were some animals on a boat.
The animals were too heavy that the boat began to sink.
很久以前，船上有一些动物。动物太重了，船开始下沉。
"We must do something before the boat sinks", said the dog, "some of us
have to jump into the sea so to reduce the burden of the boat".
“我们必须在船下沉之前做点什么，”狗说，“我们中的一些必须跳进海里，以减轻船的重担。”
"OK, then I propose that each body telling a joke", continued
the cat, "if everybody laughed, then this body can remain on
the boat, but as long as one has not laughed,he will have to jump into the water".
“好吧，那么我建议每个人都讲一个笑话，”猫继续说，“如果每个人都笑了，那么这个人可以留在船上，但只要一个人没有笑，他就必须跳进水里。”
Then, everyone agrees this smart proposal. The sheep first told a joke and
every body laughs, only except that the pig did not laugh and seemed to think someth hardly.
然后，每个人都同意这个明智的建议。羊首先讲了个笑话，每个人都笑了，只不过猪没有笑，似乎在想什么。
The sheep unwillingly jumped into the sea. After that, the bull told a joke,
which is not at all funny that no body laughed.
羊不情愿地跳进海里。之后，公牛讲了一个笑话，一点也不好笑，没有人笑。
But just when the bull is ready to jump into the sea, the pig suddenly burst into laughter,
crying "I have understood! I have understood! The joke told by the sheep is so funny!"
但就在公牛准备跳入大海时，猪突然大笑起来，大喊“我明白了！我明白了！羊讲的笑话真有趣！”
