A Joke from Beijing 來自北京的内涵笑话

A joke from Guo Degang, a famous Chinese comedian and xiangsheng actor in Beijing (See if you can get it):

北京傳來一段郭德綱的笑話：

"Once upon a time in ancient China, criminals who committed the most heinous crimes would be beheaded; and then their heads would be hung up high at the gate of the city wall, as a warning to the public. 

中國以前，對於一些罪魁禍首，是要斬首示眾，並將人頭懸掛在城門樓上。

"However, with the head hung here, flyers would come and maggots would grow. It also stank badly and affected the public hygiene. So, later on, they didn't hang the head there, and replaced it with a photo."

可是，人頭掛在城門樓上，招蒼蠅生蛆，臭烘烘的不太衛生。後來就不掛人頭，改掛照片啦。

The audience was at loss for a while, then some started laughing, some still felt bewildered.

One person shouted out loudly, "No, it's not a photo; it's a portrait!"

聽眾楞了一陣，有人大笑，有人莫名其妙，一人大喊：「不是照片，是畫像！」

Guo Degang knocked his fan on the table and said, "I am talking about a photo, not a portrait!"

郭德綱扇子一敲：「我說的是照片，我可沒說畫像呀！」

"Bravo!" Everybody clapped.

滿堂暴彩。

(以上中文是網上抄的，英文是我翻譯的。English translated by me. Chinese copied from the Internet.)