Alec's new trick

Ok, first of all a short lesson in Dutch. "Zwaaien" means "to wave at someone", and one of those lights on top of a police car or fire engine is called a "zwaailicht", literally translated "a waving light".
Why the heck am I telling you this? Well, Alec just found a new trick, and I needed to tell you the above first, otherwise you might not get the punchline.
Here in Holland, trucks that have to stop on the public road once in a while, like garbage trucks, container trucks etc, have a yellow flashing light on top, to warn other people that the truck is standing there.
Anyway, once, when Alec saw one of those lights turning, I told him as sort of a joke, that that light is a "zwaailicht" and that it is waving to him, and he should wave back. If you don't get the joke, that's ok,......he didn't get it either.
But somehow this got stuck in his little head a little bit, since a few days ago, we were waiting for the traffic light, when a truck with those lights passed by. So, Alec started to wave at those lights. And the funny thing is, that the driver saw Alec wave, and he turned on those lights while passing by. I couldn't see Alec's face, since he was sitting on my shoulders, but the way he was bounching on my shoulders said it all. So, I guess that his latest trick will be waving at trucks from now on.