My daughter is in a mother run preschool group and we had a Halloween party last week. Here is what we did:
Tell a story about a mother ghost who goes to the store to get white food (ghosts only eat white food) and tells her children to not eat anything while she is gone.
The first ghost eats a strawberry and turns pink.
The second ghost eats a blueberry and turns blue.
The third ghost drinks orange juice and turns orange.
The fourth ghost eats broccoli and turns green.
The fifth ghost thinks if he eats ice cream that is white he will be fine but it was chocolate chip ice cream so he turns speckled.
The mother ghost come home, scolds her ghosts, and feeds them white food so they turn white again.