See why this quit smoking campaign has gone viral

It's already being called the most effective anti-smoking ad campaign ever.

Instead of telling people that smoking is bad, a new ad from Thailand uses little kids to trick smokers into saying how shocking their own habit really is.

In the advert, called simply 'Smoking Kid', a young boy and girl approach adults smoking in public and, holding cigarettes in their small hands, ask them for a light.

With no clue it's a set-up, each adult starts explaining to the child why they shouldn't smoke - cleverly showing the adult hypocrisy of 'do as I say, not as I do'.

"If you smoke you die faster," one man tells a little boy. "Don't you want to live and play?"

"When you smoke you suffer from lung cancer, emphysema and strokes," another says.

The children hand the adults a brochure with a phone number to call for information about quitting that says, "You worry about me. But why not about yourself?"

The video, produced by the agency Ogilvy Thailand on behalf of the Thai Health Promotion Foundation, was posted to YouTube a week ago and quickly started going viral, jumping to more than 800,000 views already. The Foundation says it has had a 40 per cent increase in the number of calls asking for help to quit smoking.

What do you think of the video?