Doozy (noun)

(informal) something outstanding or unique of its kind.

Origin:

Originated in the early 20th century, of uncertain origin; possibly from 'daisy'.

Examples:

1. That last question on the test was a real doozy.
2. The traffic jam was a doozy.
3. The storm last night was a real doozy.
4. The final project for the class is a doozy.
5. The plot twist in the movie was a real doozy.