Effing & Blinding

[firefly]

Everyone knows what 'effing' is but why blinding?

[andy hughes]

It comes from the phrase "Cor blimey!" which is a corruption of the oath "God blind me!" - used in the days of more colourful language several hundred years ago, meaning "God blind me if I'm not right / telling the truth / telling a lie..." fill in the required version.

[incitatus]

Yes. Same derivation as "swearing blind".