It is an odd tradition, but it never gets missed in our family. It is used for any 'feasting' holiday.
Someone brings a relish tray. It consists of olives, pickles and (sometimes) celery with cheese. There are always canned black olives. I know-no flavor, horrible, etc. But my sister and I gobble them up while teaching any smaller/new kids how to wear them on your fingers and eat them. These days my nephews also help teach the younger ones how to do this. The entire can gets eaten before the meal. Whoever is fixing the meal is supposed to gripe about 'bottomless pits' and 'there won't be any left for dinner' and, of course, 'get out of my kitchen you ravenous beasts.' Magically, another can appears and is opened right before the meal so that the relish tray is once again complete. :>
No-one really loves the black olives. But it is a tradition and has been since we were kids...my uncle taught me to snitch olives and wear them on my fingers before eating them when I was little. He taught his daughter and my sister too. We refuse to give it up, even if it is childish and weird and even if we really prefer better quality olives these days.