Longman Dictionary of Contemporary English
barking mad
adjective
EXAMPLES FROM CORPUS
▪ Have you gone absolutely barking mad?
▪ Osbourne, of course, has been called barking mad before.
Wiktionary
barking mad
a. (context British NZ informal English) Completely insane.
Wikipedia
Barking Mad
Barking Mad is a British television program about problem pets. "Barking mad", meaning "insane", is a play on words. It was hosted by Mark Evans and Philippa Forrester. It was originally broadcast on BBC1. It is also shown outside the UK on the satellite channel Animal Planet. During the show, the team attempt to solve behavioral problems in dogs, cats and other pets, by means of intensive training and advising the owners on commands and methods of keeping control.
It is unknown when Barking Mad will return to Animal Planet's TV schedule.