off your chump
off (one's) chump
Crazy or insane. He must be off his chump to pay that much money for that old car. Am I completely off my chump for starting a business in this economy?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
off your chumpcrazy. British informal
The literal sense of chump meaning ‘a broad, thick block of wood’ led in the mid 19th century to its humorous use to mean ‘head’, with the implication of ‘blockhead’.
Farlex Partner Idioms Dictionary © Farlex 2017