My southern parent used a word pronounced keyarn to mean anything nasty. Example: "What is all this keyarn?" or "That smells keyarny" to mean stinky. I have heard that it is a word derived from the Scottish and my father was of Scottish ancestry. I also have seen this used in the UK in an online post and it was defined as a creamy looking, dirty, smelly substance found in folds and crevices of skin, etc.