Juan the smuggler comes up to the Mexican border on his bicycle.
He has two large bags over his shoulders.
The border guard stops him and asks, “What’s in the bags?”
“Sand,” Juan calmly said.
The guard says, “We’ll just see about that. Get off the bike.”
The guard takes the bags and rips them apart; he empties them out and finds nothing in them but sand, just as Juan told him at first.
He detains Juan overnight and carefully analyzes the sand for anything illegal, only to discover that there is nothing but pure sand in the bags.
The guard releases Juan, puts the sand into new bags, lifts them onto the innocent man’s shoulders, and lets him cross the border.
A week later, the same thing happens.
The guard asks again, “What have you got?”
“Sand,” says Juan the smuggler.
The guard does his thorough examination and discovers that the bags contain nothing but sand.
He gives the sand back to Juan, and the Mexican crosses the border on his bicycle.
The crossings repeats itself every day for three years.
Finally, Juan the smuggler doesn’t show up one day and the guard meets him in a Cantina in Mexico.
“Hey, Buddy,” says the guard, “I know you were smuggling something and it’s driving me crazy. It’s all I think about. Just between us, what were you smuggling?”
Juan the smuggler sips his beer and reveals his secret: “Bicycles.”