Purple Fly Poop

Zack comes running in the kitchen this morning yelling "Mommy come quick." I really do not like it when he does this because 9 times out of 10 it is nothing serious.
When I asked him what was wrong he told me there was a problem in the bathroom. Hoping there wasn't tons of water all over the floor I went in to see what the problem could be.
"Look mom there is some kind of sticky stuff over here." While shaking my head in disbelief I let him know it was food from his hands. Now he tells me not so politely I might add that I am just wrong because he didn't get any food on the walls. I try to get him to understand that it really is food that came from his hands when he touched the wall while turning on the light switch.
Only my kid would respond back to that with "But Mom it wasn't me, it's not food, it is purple poop from a fly!" "Zack it is not purple fly poop." "Oh yes it is Mommy."

Later on I am telling Kris about this and Zack lets out a laugh and says "Oh I know what it could be, I bet it was jelly from the peanut butter and jelly sandwich."

And this is what I live with.