平安夜
ping an ye
There is a tradition that's becoming popular, on Christmas Eve, to give out apples.
Many stores have apples wrapped up in colored paper for sale. People give apples on Christmas Eve because in Chinese Christmas Eve is called 平安夜 (ping an ye).
If we breakdown the phrase:
平安: means peace or peaceful
夜: means evening or night
This has been translated from the carol 'Silent Night'.
So the relation of this with apples is because the word for apple in Mandarin is 苹果 (ping guo) which sounds like the word for peace 平安 (ping an).