Yep, the other day (in a BMW) I pulled out of the inside lane of a 70mph dual carriageway to go up behind a 106 doing 40mph in the fast lane, of the otherwise empty road, rather than just undertaking it, to be greeted by the driver giving me the finger and pepper shaking gesture and the passenger turning round to give the same. I pulled into the inside lane and undertook, I know it's not big or clever and honestly not something I do often, but their behaviour had not exactly set the cleverness bar very high. At the end of the carriageway they pulled up behind me in the queue at the roundabout and proceeded to beep and shout abuse.