What am I on about? Phrases which arrive through slips of the tongue, and stick around. Too many metaphors, I know, but stay with me a moment.
An example is 'early doors' which is generally assumed to have originated with football manager Ron Atkinson - famous for his expressive but sometimes mangled English (see this nice fanclub website on 'Ronglish'. It is used to mean 'early on' but no one knows where the doors bit comes in.
In our own information design world, we come across the term 'heads up mapping', which refers to maps that are oriented not with north at the top, as is conventional, but so the direction you are facing is at the top. In the research environment, I have seen this referred to as 'forward up', and this makes more sense to me. But because it is the way maps are shown on heads-up displays in aircraft cockpits, the term has slipped across to refer to map as well as the display.
Personally I am not convinced that forward up mapping works best for everyone. But more on this another time.