Definition of bone ticket in English:

bone ticket

noun

historical, rare British
  • A token used in lieu of a ticket for a seat at a theatre or opera house, awarded to prominent actors and patrons for the use of their friends, family, etc.

    Such tokens were made of bone and typically inscribed to identify the owner, who could lend them out for free or charge for their use.

Origin

Late 18th century; earliest use found in Town and Country Magazine.