The collarbone of a chicken or turkey is traditionally removed from the bird and left to dry out in the sun. It has a 'V' shape, which means that it can be held by two people at once, with one to each end.
The 'wishbone' is gripped by the pinkie finger of each person, who then both pull in the opposite direction.
When the bone snaps, the winner is the one who ends up with the largest piece of bone. The winner must close his eyes and make a wish.
This wish must never be spoken out loud and must remain a secret or else it will never come true.
The name 'wishbone' is believed to have come from the ancient Romans who removed the birds entrails and read the future in them, meanwhile they laid the collarbone out to dry in the sun and people seeking special knowledge from the gods made a wish upon this bone.
Another reason that it is believed that people started thinking the wishbone lucky was because people were sure that hens and cocks were fortune tellers in spirit, since they were able to foretell the break of the day.