driver hitting lorry side
Coming of a ferry the port police noticed a lorry driver getting out and hitting the side of the lorry. Strange thing to do they though so decided to follow him.
Every so many miles he would stop and get out and hit the lorry side.
Eventually the policed decided to stop him and ask what he was doing.
The driver explained that the lorry was only capable of a 7.5 ton load and he had 9 tons of parrots in the back. So by banging the lorry side it made the birds fly around inside and got the load down to 7.5 tons
See explaination for everything. If you believe that then let me sell you ice cube in tha Artic