mad as a

(as) mad as a hatter

1. Crazy or deranged; particularly eccentric. My grandfather came back from the war as mad as a hatter because of all the horrible things he saw. I'll be mad as a hatter if I have to deal with these screaming toddlers for much longer. My family thinks I'm as mad as a hatter just because I practice a form of alternative medicine using magnetic fields.
2. Particularly cross or angry. Mom was mad as a hatter after I dented her brand-new car. John gets as mad as a hatter when he starts losing.
See also: hatter, mad

(as) mad as a March hare

1. Crazy or deranged; particularly eccentric. My grandfather came back from the war as mad as a March hare because of all the horrible things he saw. I'll be mad as a March hare if I have to deal with these screaming toddlers for much longer. My family thinks I'm as mad as a March hare just because I practice a form of alternative medicine using magnetic fields.
2. Particularly cross or angry. Mom was mad as a March hare after I dented her brand-new car. John gets as mad as a March hare when he starts losing.
See also: hare, mad, march

mad as a

hatter/March hare
Crazy; mentally deranged.
See also: mad
References in classic literature ?
At the hearin' of this, ye may swear, though, I was as mad as a grasshopper, but I remimbered that I was Sir Pathrick O'Grandison, Barronitt, and that it wasn't althegither gentaal to lit the anger git the upper hand o' the purliteness, so I made light o' the matter and kipt dark, and got quite sociable wid the little chap, and afther a while what did he do but ask me to go wid him to the widdy's, saying he wud give me the feshionable inthroduction to her leddyship.
if it wasn't mesilf thin that was mad as a Kilkenny cat I shud like to be tould who it was!
Thrue for you, Sir Pathrick," it said as plain as iver a squaze said in the world, "Thrue for you, Sir Pathrick, mavourneen, and it's a proper nate gintleman ye are -- that's God's truth," and with that she opened her two beautiful peepers till I belaved they wud ha' cum'd out of her hid althegither and intirely, and she looked first as mad as a cat at Mounseer Frog, and thin as smiling as all out o' doors at mesilf.