Using the black sharpie, draw a pumpkin face on the front of your Ziplock bag. Get as spooky or as goofy as you like!
Pour vinegar into the Ziplock bag until it's about a quarter full. Add several drops of orange food coloring and swirl it around to give it that perfect pumpkin hue.
Place a tablespoon or two of baking soda into the center of the paper towel. Fold it up into a small square or packet.
Carefully place your baking soda bundle into the vinegar-filled bag but don't let them mix yet. Seal the Ziplock bag tightly.
Now, with everything set, shake the bag a little to let the vinegar soak into the baking soda bundle. Get ready to watch your pumpkin come alive with fizz and bubbles!