When they work up the nerve to take a closer look, guess what's inside?
Vegetables (any that you can hollow out)
Candy (raid the pantry!)
Ziploc baggies (optional, if you have candies that are unwrapped)
Carefully hollow out your vegetables and remove seeds, etc. I cut the bottoms off the cabbage and brussel sprouts then with a paring knife cut out the core. Place candy inside, put back together, and arrange on a plate. Serve as "dessert". April Fools! Use leftover veggies for soup or stir fry. Here's a video tutorial on getting the candy in the vegetables:
You can check out some other fun April Fools Day ideas here. Have fun!