This episode uncovers various theories behind why and how we use certain non-verbal gestures to communicate, along with the origins of the terms that describe them. Discover the surprising history behind gestures like the high-five, said to be popularised by American baseball, and elbow touching, first suggested by the World Health Organization in 2006. The word smirk, once meant "to smile," before the emergence of the word smile itself. We also look into gestures like kissing the teeth, shaking hands, nodding the head and blowing out birthday candles.