TO GO WITH AFP STORY BY NATALIA RAMOS Several coloring books for adults  for sale in Sao Paulo, Brazil, on June 23, 2015. Considered as 'anti-stress' passtimes, one million copies of coloring books have been already sold in Brazil and even got a new category: sex to colour.  AFP PHOTO / Miguel SCHINCARIOL        (Photo credit should read Miguel Schincariol/AFP/Getty Images)