Pumpkin Oobleck

Materials: Insides of a pumpkin minus the seeds, water, blender, cornstarch 

Separate the seeds from the inside of the pumpkin.
Place the pumpkin goo in the blender with some water.
Blend.
Keep adding water and blending until you get a smooth, thin consistency.
Add 1/2 cup of cornstarch to an empty bowl.
Take 1/2 cup of your pumpkin goo and slowly add it to the cornstarch until you have the consistency you like.
Usually a 1:1 ratio of cornstarch to water {or in this case pumpkin goo} works well.
Just play with amounts until you are happy.