Ill-fortune is said to be the result from stepping on a crack in the pavement. Present day society usually associates the superstition behind treading on cracks to the rhyme: "Step on a crack, break your mother's back" but the superstition actually goes back to the late 19th - early 20th Century and had some disturbing associations that I will spare you from here.
Stepping on cracks also had significance for children. In the mid-20th Century it was popular to tell children that if they stepped on the cracks in the street, they would be eaten by the bears that congregate on street corners waiting for their lunch to walk by.
