Referring to someone as an idiot or being stupid.

A term used to reference cannabis/marijuana/weed.

The exact doube of (another person or thing)

A term used to describe Irish people, particularly the ones who immigrated to the US in there masses, during the late 1800's - early 1900's. They would typically have blue eyes, and were nicknamed 'duck eggs' as actual duck eggs often have blue tints in them.

Someone who is useless

nothing; use with aim

A decade is 10 years, and well.. a duckegg is 12 years. Although it isn't usually duck eggs, eggs from the store most of the time come in an egg carton of 12. Therefore a duckegg is 12 years.