Bog standard
WiktionaryText
Etymology
The origins of the phrase are uncertainhttp://www.bbc.co.uk/worldservice/learningenglish/radio/specials/1728_uptodate/page25.shtml. It has been proposed that it is from early Meccano sets that were labelled box standard or box deluxe and this is the origins of the British expressions bog standard and the dog's bollocks respectively.
Another suggestion is that bog standard refers to "British or German standard", a statement that has been purported to appear on engineering drawings prior to the second World War. At this time British and German engineering was in its heyday and therefore this mark was intended to be a reference to practices entailing a high standard of quality. It could be possible that the abbreviation 'BOG' and its colloquial British use to refer to the toilet could over time have caused bog standard to evolve into a humorous phrase referring to mundane, rock-bottom or lowest common denominator practices.
British etymologist and writer, Michael Quinion http://www.worldwidewords.org/qa/qa-bog1.htm writes about the etymology of this phrase and dismisses the engineering standard explanation as "hardly likely" without justification. However he also states:
"It first appeared in writing in the 1980s, seemingly out of the air. Several subscribers have told me that they remember it from the late 1960s and early 1970s in Rolls Royce and Ford factories and from other engineering environments."
If true, this does tend to lend support to the hypothesis that bog standard refers to British or German standard because people working in engineering companies at the time are likely to have been exposed to the phrase from engineers and their technical drawings before it worked its way out into popular culture and lost its original grounding.