A motorway police patrol is driving down the motorway when they see a truck driver pull over, walk to the side of the truck and with a tyre lever, bang on the side of the truck a few times, and then drive away.
A couple of miles down the road the driver does the same thing.
A few more miles, same thing.
They pull the truck over and asks the driver to explain himself.
The driver explains, “Well, my load limit is ten tons, and I’m carrying fifteen tons of parakeets, so I keep some of them flying around.”