irre
crazy
Colloquial for crazy, insane, or unreasonable. Can refer to people or actions.
Du bist doch irre, bei diesem Sturm nach draußen zu gehen!
You must be crazy to go outside in this storm!

crazy / awesome
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crazy
Colloquial for crazy, insane, or unreasonable. Can refer to people or actions.
Du bist doch irre, bei diesem Sturm nach draußen zu gehen!
You must be crazy to go outside in this storm!

The word 'irre' is related to 'der Irrtum' (mistake) and the verb 'irren' (to be mistaken, to wander around). The original meaning of having gone off the right path developed into today's colloquial meaning 'verrückt' (crazy).
Er irrte stundenlang durch den Wald.
He wandered through the forest for hours.
The meanings 'verrückt' (crazy), 'sehr' (very), and 'großartig' (great) are almost exclusively part of colloquial language. In formal or written contexts, the word is usually avoided.
Die Party gestern war der irre Wahnsinn!
The party yesterday was totally insanely awesome!
As an adverb, 'irre' is placed before an adjective or another adverb to intensify it. In this function, it is not declined.
Der Film war irre spannend.
The film was extremely exciting.
Whether 'irre' means something negative ('verrückt' = crazy) or positive ('großartig' = great) depends on the context. If it refers to a risky action, it is usually negative. If it describes a thing or an experience, it is often positive.
Ein irre gefährlicher Plan!
An insanely dangerous plan!
The meaning 'falsch' (wrong) or 'im Irrtum' (mistaken) is outdated and is now only used in very elevated language or in literary texts. It is often found in the fixed expression 'irre sein' (to be mistaken).
Der Gelehrte erkannte, dass seine bisherige Theorie irre war.
The scholar realized that his previous theory was mistaken.
very
'sehr' and 'irre' can both intensify something. 'sehr' is neutral and fits in almost any context, including school, work, or formal situations. 'irre' is colloquial and sounds stronger and more emotional. As an intensifier, 'irre' means roughly 'very' or 'extremely'. If you want to write in a factual or polite way, 'sehr' is safer. Among friends, 'irre' often sounds more natural when you want to show enthusiasm or strong feelings.

Im Gespräch war ich irre nervös und habe fast kein Wort gesagt.
During the conversation, I was extremely nervous and barely said a word.
Mein Vater ist sehr stolz auf seine Familie.
My father is very proud of his family.