The phrase 'Doozy' is used to indicate that something is an extraordinary example of its kind; very good, bad, severe, big, etc.
Example of Use: “That car crash was a doozy.”
While there are a few theories about the origin of the term 'Doozy,' which is also spelled 'Doozie,' most etymologists agree that the word is a play on the name of a common flower, the daisy. The word 'daisy' was once English slang for something that was of particular excellence, and many examples can be seen in print. One of the best is from Thomas Chandler Haliburton’s 1836 The Clockmaker: “I raised a four year old colt once, half blood, a perfect picture of a horse, and a genuine clipper, could gallop like the wind; a real daisy, a perfect doll, had an eye like a weasel, and nostrils like Commodore Rodgers’s speakin’ trumpet.”