(as) daft as a brush

slang Strange or silly. Primarily heard in UK. Quit being as daft as a brush—it's too dangerous to play on this busy street! Everyone thought I was daft as a brush growing up—my head in the clouds, lost to dreams of impossible things. I know some of my students think I'm as daft as a brush because of my weird methods.

daft as a brush

BRITISH

If someone is as daft as a brush, they are very silly or stupid. She was as daft as a brush. Couldn't say anything with any sense in it. Note: This expression may have come from `as soft as a brush', as both `soft' and `daft' can mean stupid. Alternatively, it could have come from a fuller version, `as daft as a brush without bristles'.

(as) ˌdaft as a ˈbrush

(British English, spoken) (of a person) very silly