Even if you grew up in the days of canned vegetables and over-boiled meat, you still probably have several favorite meals from childhood. So do your friends. Plan a potluck dinner where everyone shares his favorite dish, which you can divide up in any number of ways. For example, the host will supply the entrée, and each guest brings a side dish or dessert. Or you can assign everyone to a category (appetizer, sides, salad) and the final dish will be revealed at the party.
During dinner, guests can explain how their dishes were created, and tell any favorite family stories associated with it, such as the Thanksgiving when Aunt Dorothy pulled out this very gelatin mold from her fridge and it slid onto the floor. Extra points go to guests who bring the recipe with them or a photo of them as a child during the time they typically ate the dish they brought.
If everyone at the party is roughly the same age, play background music from that era, or create a mix with songs popular from every guest's childhood.