Definition of postman's knock in English:

postman's knock

noun

British
  • A game, played especially by children, in which imaginary letters are delivered in exchange for kisses.

    • ‘So long as I don't have to play Postman's Knock with any of them, I'm happy to welcome them in for Christmas.’
    • ‘Hey, I know, let's all get completely drunk and play "Postman's Knock"!’

Pronunciation:

postman's knock

/pəʊstmənzˈnɒk/