Juan comes up to the Mexican border on his bicycle. He's got two large bags over his shoulders.©JOKEDEMO.COM

The guard stops him and says, "What's in the bags?"©JOKEDEMO.COM

"Sand," answered Juan.©JOKEDEMO.COM

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.©JOKEDEMO.COM

He detains Juan overnight and has the sand analyzed, only to discover that there is nothing but pure sand in the bags.©JOKEDEMO.COM

The guard releases Juan, puts the sand into new bags, hefts them onto the man's shoulders, and lets him cross the border.©JOKEDEMO.COM

A week later, the same thing happens. The guard asks, "What have you got?"©JOKEDEMO.COM

"Sand," says Juan.©JOKEDEMO.COM

The guard does his thorough examination and discovers that the bags contain nothing but sand.He gives the sand back to Juan, and Juan crosses the border on his bicycle.©JOKEDEMO.COM

This sequence of events if repeated every day for three years. Finally, Juan doesn't show up one day and the guard meets him in a Cantina in Mexico.©JOKEDEMO.COM

"Hey, Buddy," says the guard, "I know you are smuggling something. It's driving me crazy. It's all I think about..... I can't sleep. Just between you and me, what are you smuggling?"©JOKEDEMO.COM

Juan sips his beer and says, "Bicycles.