It has been labelled "heartbreaking" and one of the most effective anti-smoking advertisements ever.
The new public service announcement from Thailand shows two small children approaching adults who are smoking and asking them for a light.
Not one of the adults shown in the ad gives the children what they ask for.
Instead the adults who have no idea they are being set up begin giving the children earnest lectures on why smoking is so bad for them.
"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 then reveal their trump card, a brochure they hand the adults which reads: "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 uploaded to YouTube a week ago and has since gone viral, attracting more than 350,000 views.
The foundation has reported a 40 percent increase in the number of calls it has received about how to stop smoking.