You're all the same!"

A Chinese walks into a bar in America late one night and he saw Steven Spielberg. As he was a great fan of his movies, he rushes over to him, and asks for his autograph. Instead, Spielberg gives him a slap and says, "You Chinese people bombed our Pearl Habour, get outta here."
The astonished Chinese man replied, "It was not the Chinese who bombed your PearlHarbour, it was the Japanese".
"Chinese, Japanese, Taiwanese, you're all the same," replied Spielberg.
In return, the Chinese gives Spielberg a slap and says, "You sank the Titanic, my forefathers were on that ship."
Shocked, Spielberg replies, "It was the iceberg that sank the ship, not me."
The Chinese replies, "Iceberg, Spielberg, Carlsberg, you're all the same.

And while we are playing around with words, can you answer this question?
When is a door not a door? .)