hare-brained idea

Translations
безумная идея
He had a hare-brained idea to travel around the world in a week.
У него была безумная идея путешествовать вокруг света за неделю.
Definitions
A hare-brained idea refers to a plan or suggestion that is foolish, impractical, or lacking in common sense.
Words
harebrained

adjective
безрассудная
idea

noun
идея