1570s, "diseased, sickly," from craze + -y (2). Meaning "full of cracks or flaws" is from 1580s; that of "of unsound mind, or behaving as so" is from 1610s. Jazz slang sense "cool, exciting" attested by 1927. To drive (someone) crazy is attested by 1873. Phrase crazy like a fox recorded from 1935. Crazy Horse, Teton Lakhota (Siouan) war leader (d.1877) translates thašuka witko, literally "his horse is crazy."
With great speed or effort: ate chocolate like crazy
Extravagantly; wildly; violently: tearing around like crazy/ Then everybody laughs like mad (entry form 1653+, variant 1924+)
Excellent; splendid; cool: If you like a guy or gal, they're cool. If they are real fat, real crazy, naturally they're real cool (1940s+ Jazz musicians)
An insane or eccentric person; loony: We're going to prevent the right-wing crazies from bombing and destroying (1867+)