Hi,
Christmas crackers are little gifts wrapped up in a tube, and tied on both ends. They make a popping sound when you open them. Sometimes they have toys in them, paper hats, etc.
I am a Canadian, and only 23, and I know this!
They are usually sold in boxes of ten at the store. You can indeed get them in North America-- I always szee them in Sears/Walmart. Usually they are put on top of the dinner plates to be opened prior to Christmas dinner.
Hope this helps
Jenn