Bonkers

Bonkers meaning crazy or mad is British slang from the mid-20th century. It is often used with intensifiers as in “stark raving bonkers”. Its origin is unknown but some maintain that it may have originated from an earlier naval meaning of bonkers that meant light-headed or slightly drunk. Londoners sometimes refer to the head as a ‘bonk’ thus the step from bonk (head) to bonkers (mad in the head) seems plausible.