As someone who also carries a very small child in the back of his Scoob from time to time, I can totally empathise with your frustration, but your three-year-old boy isn't going to appreciate that tactic much. Better to slow down until the t**t passes, or even pull over to let him past if need be. Always better to have a bonehead like that way out in front of you than right behind you, eh?
I've had dickheads drive dangerously near me while the wee one was in the car... tailgaiting, undertaking within inches of the nearside, cutting in front, etc. It can be fecking infuriating, but the last thing you want to do is to become involved - if there's one thing I've learnt while driving it's never to underestimate the stupid or dangerous lengths that another driver will go to to 'prove' himself - some of these nutters are absolutely willing to risk their own lives and yours!
Totally agree, Joe