The word "crazy" is a popular adjective that you can use to describe a person or a situation that is not normal, or the situation is extraordinarily strange. You can also use "crazy" when a person likes something or doesn’t like something.
All of this traffic is crazy. (There’s too much traffic.)
This traffic is driving me crazy.
I think I’m going crazy. (There are some big problems I’m dealing with.)
Are you crazy? (Your question or your statement defies logic.)
Isn’t this crazy? (Isn’t this situation unusual?)
Our teacher is crazy. (She’s interesting, funny, or her methods are unusual. She also could be suffering from a mental disorder.)
This music is making me crazy. (I’ve heard too much of it.)
They’re crazy about the Beatles. (They like the music a lot!)
My dog goes crazy when she smells beef. (She really likes beef.)
They’re not crazy about classical music. (They don’t care much for the music.)
Recently, some Americans have been using the word "crazy" as an intensifying adverb in front of an adjective to mean "very." (I think this is a fad, so I don’t recommend that you do this.)