The Bad Neighbors. Short animated story narrated in American English.

There was once a man who went out to look for a job. As he was passing his neighbour's house, an important piece of paper fell out of the man's pocket.

His neighbour happened to be looking out the window. He saw the piece of paper fall, and he thought: "What a disgrace! That guy deliberately let that fall out of his pocket. He's trying to mess up the front of my house, and he's being sneaky about it, too!"
But instead of going out and saying something, the neighbour planned his revenge.

That night, he took his waste-paper basket and went to the man's house. The first man also happened to be looking out the window, and saw what happened. Later, when he was picking up the papers which had been dumped on his porch, he found the important piece of paper that he had lost. It was torn into dozens of pieces. He thought that his neighbour had not only picked his pocket, but had had the cheek to mess up his doorway with rubbish.

He didn't want to say anything. Instead, he started plotting his revenge. That night he phoned a farmer to make an order of ten pigs and a hundred ducks. He asked that they be delivered to his neighbour's house.

Of course, the next day, his neighbour had quite a bit of trouble trying to rid himself of so many animals and their accompanying pong.

Sure that this had been a dastardly trick pulled by his neighbour, as soon as the second man had gotten rid of the pigs and ducks, he again started planning his revenge.

And so it went on.

They continued trying to get their own back on each other, and each time their acts of revenge got bigger and more ridiculous. The dropping of that single piece of paper ended up invoking a rock band, a fire siren, the driving of a lorry into a garden fence, the throwing of a hail of stones at windows, the firing of a canon, and finally the dropping of a bomb which destroyed both men's houses.

Both ended up in a hospital, and had to spend quite some time sharing a room there. At first they refused to speak to each other, but, one day, tired of the silence, they got to talking. As time passed, they became friends, until one day they finally dared discuss the piece of paper incident. They realised that it had all been a misunderstanding, and that if they had talked to each other on the first occasion - instead of jumping to conclusions about bad intentions - then none of this would have happened. Even better, they would still have their houses.

However, in the end, the fact that they were talking, and had become friends, helped them greatly to recover from their wounds, and to work together to rebuild their houses.