The SLIMY GOO experiment

Xander and AJ have been taking advantage of the 85+ degrees the last few days. The trampoline is the favorite spot. They each have their own hose and they go wild. Mom gets to sit on the porch swing and read. I was sitting outside yesterday listening to them play. They had a blue Tupperware mixing bowl and were filling it with water, grass and rocks. The explanation was, "Stone Soup". A few minutes later I hear them spitting. Not JUST spitting, I believe the term is "Hocking". I glance up and see their heads next to each others. The boys are taking turns spitting into the bowl.

"Ewww, that's gross!" I say to them.
AJ responds with, "Mom, it's not gross, it's SCIENCE!"
"How is spitting science?" I asked.
"Well", says AJ, "we are doing an experiment. We are making Slimy Goo."
"Oh really? What does spit have to do with the slimy goo?"
AJ gives me the, "DUH!" look and explains in the simplest terms he can for his not so smart mom, "Spit is the essential ingredient in the slimey part".

Next time I'll know better than to ask!