I once ate cake filled with blue coloring all day and my poop was Blue.
No lie.
My cousin also had this dog that'd eat crayons, so his poop would have fractions of the colors.
I remeber as I child I was making 'potions' and put red food colouring in it. I drank the 'potion' and had runny red poo for the day which really burned....
Maiko is also doing his Mystery Photo game soon 
