Mental. Fucked in the head. Disturbed. Cool in a fucked up way. Has also gained currency as simply: foolish.

Orig. Rhyming Slang (UK), not necessarily only used by davids.
Back in the day when consumer electronics were very expensive, often needed maintainance/repair and we were poor, Radio Rental was a large British company which rented... TV sets. (Doh!)

Often shortened to just Radio.

It’s an acronym standing for Can’t Remember A Fucking Thing. It’s usually used to describe embarrassment at being unable to remember someone (CRAFT moment); going onstage as the lead in the latest theatrical performance and your mind goes completely blank (CRAFT situation); the next morning after a night when you got pissed as a fart and woke up in bed cuddling a traffic cone and a string of fairy lights wound round your prick.