I wouldn’t be worried about the color of his poop, but eating crayons sounds like it could be quite dangerous. First, it seems as if they might be poisonous, and second, this little Pug could choke on them. There’s a reason why we don’t let our kids eat crayons, and dogs shouldn’t be allowed to eat them either.
When kids try to eat crayons at school, they get a time-out, and when dogs eat crayons, apparently, they are shamed online. The obvious solution would be to hide the crayons from this mischievous Pug, who looks pretty upset at the moment.