It's a Cantonese saying that means, "with a little knowledge, pretend to be an ambassador". It's used to deride someone for masquerading as an expert when in actuality, they know very little on the subject.
*ahem* =) That would be me, in linguaphiles. Occasionally, though, the questions and discussion are such that I can offer feedback. Something that always comes up is "how do you pronounce $THIS in Mandarin/Cantonese?"
Often, accompanying that question is "where is the stress in that term/phrase?" To which, I invariably answer, "the concept of 'stresses' and 'accents' doesn't exist in Chinese, everything is tonal." I've realized that this can be a pretty off-putting reply. It sounds like I'm dodging the question and/or being indignant about something...
And I feel bad every time the person says, "I have no clue about tones, I just didn't want to butcher it too badly."
Here's the deal: I'm enough of a "native speaker" that I don't hear the "stresses" across a few characters in a Chinese term or phrase. To me, the emphasis is dead even. But someone who doesn't hear the tones will tell me "oh, the primary stress is here and the secondary is here." And I go, *blink* *blinketty* *blink*. I have learned that, statistically, the first and fourth tones are more likely to be interpreted as the "stress"... just because. And I'm starting to figure out how to use this to get a more accurate pronunciation out of a non-Chinese speaker.
The Chinese language does not assign meaning to voice volume emphasis like English does. A native speaker likely does not hear the stress. Whenever our native language does not assign meaning to a particular linguistic element, we will have some degree of difficulty with it in a foreign language. Conversely, this would be why an English speaker will have problems with tones — we're listening for the emphasis and mostly ignoring the tonality. We don't completely ignore tonality, but it's a lot more subconscious and it expresses something very different in English.
This is precisely why the Japanese think that the United States has a federal erection every four years. The 'l' and 'r' do not make a semantic difference in Japanese.
We don't hear glottal stops in English. Do you hear the extra consonant in front of the word "apple"? Do you hear that it's missing when you say "an apple"? Very likely not. =)
Without training, native speakers don't naturally make the best teachers of a language for exactly this reason.
* Note 1: "baan3" is supposed to be "baan6"; "baan3" is "to hit or strike". "to pretend" has the same tone as "doi6".
* Note 2: if you save all those WAV files, duplicate the siu2.wav so that you have two of them and pull them into Winamp, it's amusing to hear her actually say the expression. =)