A: John said he wants to build a plastic car and drive around the world.

B: He is always doing strange things. He’s as mad as a hatter!

Note: “As mad as a hatter” is a colloquial English phrase used in conversation to suggest lightheartedly that a person is suffering from insanity. It is believed to emanate from Denton, Tameside in the north of England, where men predominantly worked in the hattery industry, which used mercury in the hat making process. Mercury poisoning causes symptoms similar to madness. The earliest known appearance of the phrase in print is in an 1829 issue of Blackwood’s Edinburgh Magazine. There is also the famous character of the Mad Hatter in Lewis Caroll’s novel “Alice in Wonderland.”