Inside each cracker is a little friction-operated firework, which goes "SNAP!" when two people take hold of either end and pull. Then a small charm or gift falls out of the torn cracker (usually a cheap toy, but in the more up-market ones you might get a miniature set of playing cards or a pen or some dice) also a paper party hat and a slip of paper with a lame joke on it:
https://www.subsim.com/radioroom/sho...47&postcount=1)
The crackers are usually placed next to each table setting so that diners can pull them with the person sitting next to them. I hate the things but Moira loves them. She hasn't bought any this year... good-oh!