We held a "Farewell to Freedom" party.
The rules for attending were: hair had to be crazy (messy, half in a pony tail half not, sticking up wild, temporary spray on wild color if the parent permitted that), clothes should clash as badly as possible, clothes couldn't be neat (buttoned improperly, one pants leg rolled up and one not), mismatched socks and shoes, etc. Smudged faces were encouraged. We informed parents that this would be a good opportunity for the kids to wear a cheap t shirt from the thrift store and clothes that would get messy.
Food was anything NOT natural, not healthy, not school-lunch or healthy after-school-snack approved and definitely not the kind of food that was normally in our pantry or fridge. We made blue Jello jigglers, mixed popcorn with a little blue food coloring, bought lots of penny candy things like wax lips and neon colored candy sticks and gummy worms, and had spray cheese from the can. (We informed parents that only desserts and treats would be served, so they didn't expect burgers and hot dogs or picnic type food). We tried to use up mismatched left-over paper plates, from assorted birthday parties and cookouts.
Games were not really planned. We just provided silly string, water balloons, cheap squirt guns from the dollar store, and let the kids run around.
Our only rule was "clean hands for eating" and we provided lots of wipes and hand sanitizers.
My kids are grown now, and so are their neighbors who came to these parties, but they all still fondly remember the Farewell to Freedom parties.