Here's a few we have fun with:
Cook something in the ground. You can find the instructions on line with a google search.
We take several layers of foil about 1 foot in length. Put a hambuger steak,onion, potatos, carrots and other veggies on the foil. Add spices. Fold up the foil so it's sealed punch a couple of small vent holes in the top. Place the packet in hot coals of the campfire. Everyone builds their own and cook it. 15 to 20 minutes cook time. Toast some french bread over the fire on a stick, butter it and eat.
Roast a whole turkey or turkey breast over the campfire on a spit. Everyone takes a turn at turning the spit.
Take a bunch of canned veggies and peel the labels off. Number each one so you will know what each one is but don't let the guests know. Have them either pick the numbers out of a hat or choose a number. Dinner is made from the choices. For six people we will have about 12 different choices, each person chooses one of the cans. Cook up a meat or pasta dish and the veggie choices.
Pizza made on the BBQ grill. Again look on google for instructions. Individual sized pizzas with an assortment of toppings,each person builds there own.