The owner initially wanted his son-in-law to show off his flair in poems, so he invited all the guests to write a poem regarding his Teng Wang Ge. Nobody dared to write anything as everyone knew the purpose of the owner. The paper and brush was passed around but no one touch it.
Wang Bo was sitting at the end of the hall as he was one of the last guest to be invited. When the paper and brush reached him, he just picked it up and started writing.
Seeing this, the owner was rather unhappy and found an excuse to leave the hall. Wang Bo, being young, was not sensitive with the behaviour on the owner and continued to write.
The servant of the owner started passing messages to the owner informing him what Wang Bo wrote.
This was the first line, it clearly stated out the location of Teng Wang Ge.
"hmph!", thought the owner.
"smart alec," thought the owner.
"not so bad, in fact," thought the owner.
*slaps the table* "Hao ah! (good)" exclaimed the owner.
He immediately stood up and went to Wang Bo's side to watch him finish the poem.
Those parts I mentioned above is not the full 序 and it is not the poem. It is just an introduction to the Teng Wang Ge and the poem.
Then Wang Bo proceeded to complete the poem.
And Wang Bo became famous.
My favourite line is 落霞与孤鹜齐飞，秋水共长天一色。Imagine the scene... awwww.. isn't it just beautiful?
I forgot where I heard this story before, I think it is from some lit books. :D
Teng Wang Ge