Yellow fever strikes the Conchords

They might look like Bret and Jemaine and they sure do sound like them. But they are Kurt and Ethan, "counsellors/artistic directors/outreach community liaison" for Expressions Arts Camp, just outside Springfield.

There, they mentor kids like new arrival Lisa Simpson who has been sent there as a treat while her father and brother help Krusty the Clown pick up his Nobel Peace Prize (which is another story).

Among Kurt and Ethan's lessons for their kids is how to deal with hecklers. Their sample heckle: "I've seen more life in the Wellington Botanic Gardens!" Which leads to a deadpan discussion between the pair - "If you are not from New Zealand, it loses some of its sting," notes Ethan - while both agree said gardens are actually teeming with life.

Welcome to the Flight of the Conchords on opening the show of the 22nd series of The Simpsons.

Jemaine Clement and Bret McKenzie are the third and fourth New Zealanders to appear on the American television institution, following Sam Neill and Lucy Lawless.

"Four out of four million is a pretty good batting average," notes the show's long-time executive producer Al Jean on the phone about the number of Kiwi cameos versus our population - though the Flight of the Conchords appear for half the episode, which also comes with nods to Glee care of guest voices Lea Michele, Cory Monteith and Amber Riley.

Effectively, it's an animated encore to FOTC's HBO comedy series which they quit after two seasons.

"I'm a huge fan of their show," says Jean "and we're so pleased they let us basically steal the show. We wrote some lyrics and they did the music for a couple of songs. It was a huge part. We just let them come in and do what they do. I really miss that show so we created half an episode for ourselves."

The idea for the story line, says Jean, came from writer Tim Long who knew another writer whose daughter had gone to arts camp "and came back all artsy fartsy".

That made both a good plot for Lisa and a way to get FOTC aboard as camp counsellors.

Jean is amused to hear that the joke works on another level here - plenty of young Kiwis head off to be counsellors at summer camps in the United States.

Although now the longest-running primetime television series in American history, The Simpsons still screens, on average, to nearly seven million viewers - far more than the Kiwi duo's cult hit on pay TV channel HBO. So Clement and McKenzie were effectively playing to a whole new audience. Did The Simpsons faithful get it when it screened there in September last year?