Same word as crazy:

ape, barmy, bats in the belfry, batty, berserk, bonkers, cracked, crazed, cuckoo, daft, delirious, demented, deranged, dingy, dippy, erratic, flaky, flipped, flipped out, freaked out, fruity, idiotic, insane, kooky, lunatic, mad, mad as a March hare, mad as a hatter, maniacal, mental, moonstruck, nuts, nutty, nutty as fruitcake, of unsound mind, out of one's mind, out of one's tree, out to lunch, potty, psycho, round the bend, schizo, screw loose, screwball, screwy, silly, touched, unbalanced, unglued, unhinged, unzipped, wacky