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1.
Doing a dunsford

Also known a to have done a dunsford

To completely fuck something up, beyond recognition, usually multiple times, often in a dangerous way, but it has been know do describe any mistake made in an engineering work place.

Used mainly in engineering fields, often followed by 'cheers then' is commonly used in the UK and Europe

Believed to have originated from Rolls-Royce
Person A: ‘I think I’ve done it, again, its on the piss

Person B: ‘what? Really?!’
Person A: ‘yea it’s my seventh! I just keep doing a dunsford!’
Person B: ‘at least it’s not as bad as last time, you nearly lost an eye’
Person A: ’yea I am such a dunsford’
by R-R A Group December 01, 2011