Cockney Rhyming Slang - Radio

Radio Rentals was formed in 1932 to do just that, rent out radios, later they rented televisions and then a host of electrical items. The business model dipped considerably in the 1980s and has now ceased trading in the UK.
So what has this former British company become known for in Cockney rhyming slang? Not being beholden to too much political correctness "radio rental" is rhyming slang for mental.

Let's use it in a sentence:
"On Deal or No Deal today the guy was left with £1,000 and £75,000, the banker offered £24,000 and he turned it down, even if he'd have won the seventy five grand he'd still be radio"