Doo Ca Doo Ca
When your caca looks like doo doo so it can't be correctly classified as one or the other. Some say it's caca, some say it's doo doo. Nobody really knows, so a combination of both words are necessary in this scenario.
The man pooped on the floor but he could not identify whether or not it was a doo doo or a caca. Therefore, he decided his poop was a doo ca doo ca.