I'm over the rainbow...gone bananas, wacky, a crackpot, a complete nutter, a basket case, mad as a hatter, complete bonkers, a screwball, got bats in my belfry, crazy as a coot, lost my marbles, out of my mind, loco, got a screw loose, half-baked, warped, daft, balmy, mad, crazed...okay I'll stop now (I'm out of idioms and synonyms)