The foam that forms and stays on top of your tea when you brew a tea bag and cup of water in a microwave.

when you're hungover as shit after a spending a night drunk as a skunk

the disgusting liquid that comes out of a ketchup bottle before the actual ketchup; can also happen with mustard and any other condiment; can be avoided by shaking the bottle beforehand.

The layer of coagulant like jelly that forms on the top of certain creamy soups after sitting. This layer can easily be diminished by the stirring of a spoon.