On a more general issue, I've on occasion gesticulated at other drivers for doing stupid things, but most of the time now I feel my life is more important than letting them know they've been stupid. I think the tipping point was when a car behind beeped when we were at some red lights. My wife was driving, but from the passenger seat I made a non-rude gesture at the driver - kind of shrugging my shoulders as if to say 'what?' The car pulled onto the other side of the road and the passenger wound down the window and chucked a full can of coke at the driver's window - which, thankfully, was not open. Terrible waste of coke, of course, but the interesting point was that both driver and passenger were 20-something women. The world is full of arseholes of both genders.