be as mad as a hatter

to be crazy

Usage notes: A long time ago, people who made hats used a substance that gave them an illness which made people think they were crazy.

Her brother's as mad as a hatter.

Name	Pronounced	Usage
Suellen	soo-EL-ən	English
Waldemar	vahl-DE-mahr (German, Polish)	German, Swedish, Norwegian, Danish, Polish
Valerija	-	Serbian, Croatian, Slovene, Lithuanian
Micheil	-	Scottish
JesÚS	he-SOOS	Spanish
Pietrina	-	Italian