It was the time of the British occupation in Egypt and access to the industrial zone of the canal has been restricted. Only workers were allowed in and were occasionally searched on their way out.  Bikes being a common mean for transport at that time were how workers usually went to work.

One day, a man approached the gates on his way out with a bike and a big sac on its seat. The English officer at the gate got suspicious from that sac, he opened it just to find nothing but...sand. "This guy is hiding something", he thought. He emptied the whole sac, searched almost every grain, yet found nothing. So, he just gave it back to the guy and let him go.

Days went by and the guy came out with a similar sac of sand in the same manner almost everyday. The officer insisted each time on searching the whole sac, every single grain, for he believed the guy will make his move one day when he gets fed up from the pointless search.

So, the officer never gave up, and the man came out with the sac of sand everyday.

It went on like that for some time. Then one day the officer received news that he would be replaced. On his last day, he approached the man and said "Alright, I give you my word as a gentleman, I shall tell no man. What's with the sac?", and the guy replied "Nothing's with the sac, it's just that I go out with a different bike everyday".

...Ania