It's one thing to write a dramatic heart-wrenching song about famine in Africa, but it's quite another to make people laugh around the subject of kids and serious illness.
I suspect Bret and Jemaine may have foreseen this challenge, so they came up with a cunning plan - they got kids to write the lyrics! Genius.
Bill Cosby knew it when he made Kids Say The Darndest Things, but what better way to lighten a subject than to get whimsical, genuine, and hilarious contributions from some young school children.
Filming said interviews and including them as a prelude to the song was even more genius, because knowing how they came up with the ideas about large bowls of teeth, or feta cheese to make kids better, only heightens the fun.
Of course turning these ideas into a cohesive song couldn't have been a straightforward exercise, even with brilliant rhyming lines like "the kids who are sick can't do their hip-hop anymore, because their tummies could be very sore", or "open up the lids, help help help the kids" already supplied.
But the pair managed to come up with a classic upbeat pop ballad that also had room for a great rap breakdown, along with the all-important exciting upwards modulation 30 seconds before the end.
Choosing a wide cross-generational range of New Zealand artists to contribute vocals was also very savvy - that way there's something for everyone. They had 21 extras in total, with some established stars like Brooke Fraser rhyming hospital with lostpital, Dave Dobbyn warning about drinking too much bubble mixture, and Boh Runga singing the word "spews" - probably for the first time ever.
Images of Sam Scott and Luke Buda of the Phoenix Foundation joyfully pogo-ing around Roundhead studios; Rikki Morris, Nathan King and Zowie singing about robbing robbers; Ruby Frost tackling the feta issue; reinforcement from Victoria Girling-Butcher, Kids of 88 and Elizabeth Marvelly; great rhyming from Savage, PNC, and Young Sid; Moana Maniapoto, Peter Urlich, Maitreya, and young gun Massad explaining that crazy financial system; and excellent vocal gymnastics from Cherie Mathieson as she tells us where to put all those teeth for the tooth fairy - they all helped to form an instant Kiwi classic.
Undoubtedly there are going to be annual sing-alongs at Christmas in the Park, so you'd better buy the song and start learning all the words off by heart.
We've gotta make sure they raise at least "a million, and a hundred, ten and twenty one dollars", after all.
-TimeOut