Performing with just their guitars, Jemaine crooned in a Nasally baritone, while Bret contributed higher notes in the chorus - "It's business, it's business time".
It was stealth humour. By that I mean not only were we unaccustomed to the genre, we were unaccustomed to how good it was.
According to their best-known song Business Time, "Wednesday night is business time", which, of course, is a euphemism for a mid-week roll in the hay.
That in itself is a euphemism, so if the penny still hasn't dropped think of Wednesday in terms of hump day.
Anyway, it's all part of their charm. Lewd, but ambiguous enough to sneak under a prude's radar. Deviant, but innocent enough to pass as a family show.
These two Kiwi comics have since made it big in one of the toughest and most impenetrable US markets - HBO sitcom.
If it were up to me Flight of the Conchords would be a mandatory pop-culture item on our schools' curriculum. Not only are they extraordinarily good, they're a genuinely magnificent export.
And just when I thought I couldn't be any prouder, Bret picked up an Academy Award last month for his song Man or Muppet.
It wasn't the Oscar so much, it was his backstage comment to US media that had me buzzing.
Asked how a small country like New Zealand produced so many award-winning artists, he responded: "It's a great place to grow up. You can do whatever you want there. Whereas in America I think everyone's obsessed with their careers. In New Zealand you get to just live your dreams".
Boom. Take that, Hollywood.
It's a coup to have them at the Hawke's Bay Opera House and it's a coup to have them here first. But most importantly it's a coup to have them here on a Wednesday - "business time".
