Just read every one of these posts, and some corkers in there! However, I have one particular hate which does drive me nuts: People driving the wrong way up/down supermarket car park lanes! They are one way, and have arrows marking their direction! Yes, they are wide, but that is to allow people to park safely! My local Tesco is particularly bad for it, especially women who just look at you blankly as you point to the arrow on the floor!
In response to some of the others - sidelights are not illegal - in fact in built up areas with street lights you are allowed to drive with only your sidelights on - dipped beam is only a legal requirement outside built up areas. I used to hate people for using only sidelights, until I found this out!
And although I don't drive a wagon, I spent 4 years working for a haulage company and I can assure you the lack of respect for, and knowledge of wagons is horrendous - people seem to think they are the same to drive as a 8 foot car! Although like someone else said, foreign wagons are a different matter - far too many are illegal killing machines.
And, finally, the 'hand on mouth' thing had me in stitches - for years, growing up I watched my dad do it - now, like everyone else, I find myself doing it! A proper Peter Kaye observation there!