For the BBC Comedy series Red Dwarf the writers invented a swear word 'Smeg' as no swearwords would be broadcast by the BBC.
Smeg is a vulgarism or expletive used throughout the series of Red Dwarf. Although no specific meaning is ever given, it and its derivatives such as Smegger, smeg off, smegging hell, smeghead and Smeg for brains are regularly used for swearing or as derogatory terms.
Mechanoids were programmed to obey their human masters and were not programmed to swear. However, Kryten managed to override his core programming, but could not say smeg head. The words would cause a minor malfunction, causing them to come out as "smeeeee heeee".
On a personal note I have used 'Flaming Red Flashing Firetrucks' in polite company.