If you ask anyone about their experience riding public transit, they aren’t likely to tell you that it was enjoyable. Still, millions of people ride buses, subways, and other forms of public transportation daily.

However, every once in a while there is something exceptional that happens when it comes to public transportation. We’ve all seen videos where a flash mob takes over the subway or train station. But it isn’t just music that can bring a smile to peoples’ faces. Sometimes smiles are just as contagious as yawns, and one company set out to prove just how contagious laughter can be.

Coca Cola hired a man to board a commuter train packed full of people. In the video below, you’ll see him standing in the middle of the car wearing earbuds and staring at a tablet. It isn’t long before the man starts to laugh. His laughing gets harder and louder with time. Eventually fellow commuters start looking at him and you can tell they are trying to figure out what is going on.

Yes, they’re probably judging him a bit, but as his laughing continues, eventually smiles begin creeping onto their faces. The man doesn’t seem to be phased by the staring and continues to laugh.

Little by little, the other commuters’ smiles begin to get bigger and eventually a few start giggling. As the man continues to laugh, others begin laughing too.

After a while, the smiles and laughter spread throughout the entire car and many of the commuters are laughing hysterically, either at the man or with him, but does it really matter?

The point of the video is that happiness starts with a smile. All it takes to start a chain reaction and brighten someone’s day is a simple smile. Check out the video below and be sure to share it with your family and friends.