1. Why do we tap our mouth when we yawn? The gesture has nothing to do with the intention of hiding mouth anatomy, dirty teeth or the intention to impede the spread of germs, but a more profound meaning.

In ancient times, making the cross sign in front of the mouth when yawning impeded the devil to enter the body and establish there his dwelling. That's why mothers closed the mouth of the toddler or made the cross sign in front of the mouth when infants yawned. From this ancestral custom derives the modern day gesture.

2. Why do we pull kids by their ears? In African and Eastern cultures, the ear was the object of varied symbolism: it represented from the cosmic intelligence of the Hindu myth of Vaishvanara to sexuality for the tribes of Bambara and Dogon of Mali. Amongst Chinese people, large ears were a signal of wisdom and immortality; it is said that the philosopher Dao, the founder of the Daoism, had 17 cm (7 in) (!) long ears, being nicknamed "Big ears". Probably the Oriental beliefs reached the Western world in time.

By pulling by the ears a person on this birthday, we wish him/her to have both a long life and acquire major wisdom in time.

3. "Horny man" in English has one meaning, but "cocu" in French, "cornudo" in Spanish, "cornuto" in Italian, "incornorat" in Romanian - even if they all translate literally by "horny" - in fact mean 'cuckold'. The origin of this expression comes from the Byzantine Empire, during the times of the emperor Andronikos Komnenos (1118-1185). The women-lover emperor had many mistresses and conferred from time to time to their husbands the right of hunting on the imperial lands. When a man received this right, the had the obligation to place some deer antlers over the house's entrance, a signal he was gone hunting. The emperor could pay a visit to the mistress in the meantime. This is just one variant.

4. In medieval Europe, nobles were said to be of blue blood. Why? This comes from the medieval Spain. Before the invasion of the Arabs, the noble class was made by Visigoths, a nation of blond-haired, pale-skinned people of Germanic roots. Spanish nobles wanted to say they are not dark skinned like the invading Arabs, but their roots lied amongst the Northern Europeans, with their pale skin and visible blue veins.