I've heard "En-Zedder," which sounds idiomatic and not too disrepectful. I don't like the stupid sound of "kiwi," and if I were a New Zealander I'd hate it--"Is that all you know about New Zealand?--How stereotypifying."
I would suggest that you refrain from calling the sound of the word "kiwi" stupid in front of most Kiwis. Most New Zealanders are proud of their national bird and use the name "kiwi" to refer to themselves. You are quite entitled to think that word sounds stupid, but saying so to most New Zealanders is almost guaranteed to cause significant offence. The word which has the "stupid" sound to which you refer is onomatapoeic. The bird's name comes from the sound of its call, and since the bird is native onlyto these islands, its use as a national symbol and badge of identity is understandable. If you delight in giving offence, by all means go ahead, but by most definitions calling people what they wish to be called is considered courteous. Walekam salaam, noho ora mai.