when i was super-little i lived next door to a little girl that was about the same age as me so our parents had us play together a lot.
she had a baby doll that was supposed to teach you about child-rearing or something? it came with a bunch of packets of colored ‘food’ that had the consistency of apple-sauce but was in various bright colors like blue, red, etc.
after you fed the doll it would ‘poop’ in its doll-diaper but the poop was the same bright color when it came out as it was when it went in
i remember being really disappointed when i discovered that feeding it every color at once did not, in fact, result in rainbow poop