The Flight of the Conchords star took gold at the glitzy ceremony on Sunday (26Feb12), winning the Best Song prize for his contribution to The Muppets movie, a track called Man or Muppet.
The New Zealander admits his speech was put together in his shower as he thought he had no chance of winning, but he was so nervous he barely slept for a month before the ceremony.
McKenzie tells Radio New Zealand, "When they did actually call my name, I was strangely calm. But leading up to it, I haven't slept properly since I got nominated a month ago. I spent two days practising (a speech) in the shower. I knew that if I didn't prepare something, it'd be a total mess... I really thought I wasn't going to get it so I was practising my face.
"I was tempted to try and smuggle a Muppet in under my coat and bring it out and do Man or Muppet."
He adds, "It was a pretty amazing night. I've been here six or seven years, on and off, but (there's) nothing quite like partying with an Oscar in your hand."