The hastag #HappySoundsLike is buzzing on Twitter. Tens of thousands have been compelled the share their own personal happy songs, the world over. While it may all seem a little trivial, there is some serious weight behind the campaign: the United Nations has called on music lovers to "use the international language of music to show our solidarity with the millions of people around the world who suffer from poverty, human rights violations, humanitarian crises, the effects of environmental degradation and climate change," said UN Secretary General Ban Ki-moon.

He also shared his favorite 'happy song': Stevie Wonder's "Signed, Sealed, Delivered I'm Yours." Your very own happy songs can be submitted to the global playlist through the #HappySoundsLike hashtag all day on March 20, with the final playlist streaming at happysoundslike.com.

From 40s classics to contemporary R&B

International celebrities have also jumped on board to set the happy mood, with a hugely varied selection. US actor Michael Douglas swears by 1957's "Zip-a-Dee-Doo-Dah" by James Baskett, while British singer-songwriter James Blunt has offered "We Are Young" by Fun - a song he says "celebrates the moment." African singer Angélique Kidjo says she loves Miriam Makeba's "Pata Pata," as the happy tune continually builds and the "groove is absolutely irresistible." British superstar Ed Sheeran added the R&B hit "Independent Woman" by Destiny's Child to the playlist and in a video message calls on the rest of the world to join in the revelry - however warns of a particularly joyous song from 2013: Pharrell Williams' "Happy." "Even though it's a happy song, a dark meaning lies behind it. Very dark…" he said winking into the camera.

Pharrell invites the world to dance

Pharrell Williams has of course joined in the "happy" action and, on the website globalhappyparty.com has invited everyone to a huge virtual party for the International Day of Happiness. Users' pictures are turned into a moving GiF and published on the page to an instrumental version of "Happy."

Of course, Williams has already got his friends hooked on the happiness bug, with pop divas Christina Aguilera and Gwen Stefani partaking, as well as filmmaker Spike Lee. The site shows hundreds of animated photographs and a global party map of where the 'party guests' come from.

Bhutan - the model of happiness

The UN decided on an International day of Happiness during a summit meeting in 2012. At the meeting Secretary-General Ban Ki-moon called for a new economic thinking which factored in "happiness and well-being." The UN chief continued: "Social, economic and environmental well-being are inseparable." The country of Bhutan is seen as a model of the pursuit of happiness - putting the happiness of its citizens before economic performance. This policy of "gross national happiness" is unlikely to catch on around the rest of the world, but on March 20 the UN aims to remind the world that happiness and the well-being of people should be a global priority.

And countries like Germany should be paying heed. While one of the top performing global economies, Germans are widely reported to be somewhat discontent. Hence, days like the International Day of Happiness can hardly do any harm.