[nutcase] {n.} An insane person.

[nuts about] See: [CRAZY ABOUT].

[nutter] {n.} Insane person.

[nutty as a fruitcake] {adj. phr.}, {slang} Very crazy; entirely mad. […]

[off one's head] {adj. phr.} Crazy; mad. * /We had no […]

[off one's rocker] or [off one's trolley] {adj. phr.}, {informal} Not […]

[out in left field] {adj. phr.}, {informal} 1. Far from the […]

[out of one's head] or [out of one's mind] or [out […]

[right out] or [straight out] {adv.} Plainly; in a way that […]

[stuck on] {slang} Very much in love with; crazy about. * […]