Pruritus or Itching

If anyone observes Maria, Ricard, Matt and Eduald closely, they may think that they just invented a new dance. It’s called: the itching rock. It begins with scratching the head with the right hand and the foot with the left.

They scratch the ear with the shoulder and the nose with the tongue. 

Why do they have itching? What is itching? Make the itching disappear or will the eventually triumph in the summer with their dance?