Jolavan Wham charged for holding up a smiley face sign

To the casual observer, it is just a photo of a man holding up a smiley face - an image used hundreds of millions of times a day in messages across the world to say "happy".

But this smiley face on a Singaporean street is different. This smiley face has landed the man holding it in court, potentially costing him thousands of dollars in fines.

And despite the risks, this smiley face has also inspired a wave of smiley faces in support.

So what exactly about this particular smiley face has upset authorities in one of the world's wealthiest and most advanced nations?

Why is this smiley face offensive?

Well, it has less to do with the smiley face, and more to do with the man holding it.

Jolovan Wham is a civil rights activist who has made a name for himself in recent years drawing attention to the issue of freedom of speech - or rather, as he would argue, the lack of it - in Singapore.

The photo was the latest in a long line of incidents involving Mr Wham which have upset the government.

Last year, it was for inviting the prominent Hong Kong democracy activist Joshua Wong to join in a conference via Skype.

On another occasion, he held a candlelit vigil for a Malaysian man executed for drug trafficking, while a silent protest on a train also placed him in the authorities' sights.