I heard this one today from Steinar Hoistad, Director of European
Operations UNIX International, at the UI Road show.

A colleague was invited to hold a speech in Japan.
Aware of his reputation as a very good speaker, he was surprised that
his audience did not react at all to any of his perfectly timed jokes
and witticisms. In fact, the audience did not react to anything he
said. Somewhat put down, he went back to his seat and a Japanese
gentleman appeared on the stage. This man had a terrific success!
People laughed and applauded, and although the original speaker could not
understand one bit of what was said. Still he started to applaud, as
the man evidently deserved praise for this perfect speech.

However, he was interrupted by the chairman of the conference:
No no, sir. You must not applaud!

Dumbfounded he protested:
But why? This man is obviously a very good speaker.

No sir, you must not applaud, he is translating your speech.