This is genius and of course it's going to work. How many times have you been sitting in the office and watched a yawn slowly set off a domino effect across the whole room? No doubt about it, yawning is as contagious as an airborne zombie virus. Even when your yawning on purpose, just to set other people off, it works. Just watching the video below made me yawn a couple times. You try to watch it without yawning. It's not easy. Best part though is that at the very end we see that humans aren't the only ones that can catch the yawn. Check out the video below for the world's most contagious prank.