Why do our tummys "growl"/rumble/talk to us :)? I know it's telling us we need to eat and all that, but what makes it rumble?

It's the digestion of food called peristalysis that moves the food through the colon and out through the bowel.

It's not what you think ;)

Here's the scoop:
Stomach noise: What makes my stomach growl? - MayoClinic.com (http://www.mayoclinic.com/health/stomach-noise/NU00189)