A sindhi comes up to the Pakistan border on his bike. He's got two large bags over his shoulders.
The guard Iqbal stops him and says, 'What's in the bags?'
'Sand,' answered the sindhi.
Iqbal says, 'We'll just see about that. Get off the bike.'
Iqbal's guard takes the bags and rips them apart, he empties them out and finds nothing in them but sand. He detains the sindhi all night and has the sand analyzed, only to discover that there is nothing but pure sand in the bags. Iqbal releases the sindhi, puts the sand into new bags, hefts them onto the sindhis shoulders, and lets him cross the border.
A week later, the same thing happens. Iqbal asks, 'What have you got?' 'Sand,' says the sindhi.
Iqbal does his thorough examination and discovers that the bags contain nothing but sand. He gives the sand back to the sindhi, and crosses the border on his bike. This sequence of events is repeated every day for three years.
Finally, the sindhi doesn't show up one day and the guard, Iqbal, meets him in a 'Dhaba' in Islamabad .
'Hey, Buddy,' says Iqbal, 'I know you are smuggling something. It's driving me crazy. It's all I think about.I can't sleep. It will just be between you and me, can you let me know what are you smuggling?'
The sindhi, sips his Lassi and says, "Bikes" :D