Other forms: kettles of fish
The expression "a kettle of fish" means "a real mess." If you accidentally scheduled three dates on the same night, you might call it a kettle of fish.
Most people who use this expression say either "a fine kettle of fish" or "a pretty kettle of fish," though what they're describing isn't fine or pretty. Word experts aren't sure why kettle of fish came to be synonymous with "a muddle," but many of them guess that it's the way fish remains look — heads, bones, and innards muddled together — that inspired the expression.