It was only recently I found out that those yellow camera looking things on pavements that you see people fiddling with are not cameras. They look like cameras and have a long neck attached to them like a camera. The amount of times I've said sorry to the people controlling these measuring things is embarrassing. There's loads of them around the West End/Soho at the moment and someone who was walking with me was like,'what, they're not cameras!' when I ducked out the way. They're used to measure the road or something, I can't find what they exactly look like but a bit like this:
http://www.dcrainmaker.com/images/2009/03/racing-the-line-understanding-how-courses-are-measured-9.jpg

Something like that only standing tall.

What mistake have you made recently? Apart from reading this thread.