Truck nutz, those are hilarious
Good heavens every time I see those things swinging I want to rip them off and throw them at the driver! D:
Imagine a child asking his mommy the universal question!
"Mommy what is that swinging back and forth?"
I guess you could make something up like a weather rock. Accurate when the truck is parked and it goes like this.
If the rock is still the weather is calm.
If the rock is swaying it is windy.
If the rock is cold it's freezing out.
If the rock is hot we're having a heat wave.
If the rock is wet it is raining.
If the rock is white it's snowing. (or someone missed!)
If you cannot see the rock it is foggy.
If the rock and truck disappear - TORNADO!
http://www.youtube.com/watch?v=E45JLnggmX8