Proof That Laughter Is Infectious Even If You Don’t Know What You’re Laughing At! [VIDEO]

If you've ever started laughing simply because someone near you was laughing, you'll appreciate this video. A woman in a subway's laughter at something on her phone becomes infectious and, before you know it, everyone on the train is laughing!

I always fall victim to this kind of situation. I love to laugh and I really enjoy seeing others smiling and laughing. So, if I'm in a situation where people around me are laughing, I can't help but join in. And why not? It makes you feel good, despite the fact that you have no idea why you're laughing.

So, here's the challenge: I dare you to watch this video and keep a straight face. I bet you can't do it!