Crazy is a crazy word hehe.
Definitions of crazy:
noun: someone deranged and possibly dangerous
adjective: marked by foolish or unreasoning fondness
Example: "She was crazy about him"
adjective: foolish; totally unsound
Example: "A crazy scheme"
adjective: intensely enthusiastic about or preoccupied with
Example: "Crazy about cars and racing"
adjective: possessed by inordinate excitement
Example: "The crowd went crazy"
adjective: bizarre or fantastic
Example: "Had a crazy dream"
adjective: affected with madness or insanity
I have no defintion for it, for me crazy is crazy, its as simple as that.
"Dude, that's crazy!" reffering to something out of the ordinary. Ordinary meaning something that Im used to.
But its all in how I express crazy. If I express it like: "Dude that's crazy!", its like "Dude, you shouldn't do that!", but "Dude, that's crazy (and with a paus on the vowel a)!", its like "Dude, that was cool, I wanna try/do it!".

- Enivid