It doesn't have any specific meaning, but it's understood to represent the joyful, celebratory atmosphere of the holiday season.
You might hear it in:
* Christmas songs: It's often used as a refrain or chorus to add a lighthearted, festive touch.
* Christmas greetings: People might use it playfully in their greetings, especially in a lighthearted way.
* Christmas decorations: Sometimes you'll see it written on ornaments or decorations, adding a touch of whimsy.
Essentially, it's a fun and playful sound that captures the spirit of Christmas.