Sometimes - when hooted e.g. for not being on the cycle path that someone thinks I should be on, I simply give a quick wave without looking back, or sometimes a kind of palms-up-what's-going-on approach & but without any verbal confrontation...
Totally ignore. Any acknowledgement of his horn blowing gives the impression he may actually be in the right. All his noise has just drawn attention to himself, if you just carry on then everyone thinks he's just a pillock making a racket. Which just about sums it all up
1. Ask him to indicate to me where the law or the highway code compels me to give way; he won't be able to, so I laugh and cycle away, shaking my head in wry amusement (to tick him off even more)
2. Tell him if he wants to argue about, to pull over and get out of the van; he's unlikely to - if he doesn't, I laugh and cycle away, shaking my head in wry amusement (to tick him off even more). If he does, I knack him.
You could argue the toss withhim re highway code, common sense etc; it may work for some, and may make others think about it afterwards. Or, you could dismount, and run towards his van waving a tin of anchovies, shouting "Raspeberry ripple? Raspberry ripple? We never had that during the war!"
What really annoys them is take a picture of the van and them with your camera phone as they then think you'll send it or call thei boss and they may be in trouble.
Only works on sign written vans however.
Really boils their blood!!