Yawning is contagious. If someone yawns in your vicinity then it’s likely you will also yawn. Yawn near a group of people and you raise the chances of someone catching the yawning bug.

Roman Atwood decided to use this strange phenomenon to create the world’s most contagious prank, travelling around the world trying to prompt people to yawn by merely yawning himself.

This video shows the results of this experiment, with Atwood having been filmed in various locales around the world yawning next to complete strangers, some of whom yawned back.

No one knows why yawning is contagious. It’s probably a survival instinct linked to our evolutionary past, but would that explain why cats and dogs can also be persuaded to yawn?