Unsolved mystery:

Juan comes up to the Mexico border on his bicycle. He has got two large bags over his shoulders.

The guard stops him and says: "What is in the bags?".

"Sand." Juan answers.

The guard says: "We will 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. He detains Juan overnight and has the sand analyzed, only to discover that there is nothing in the bags.

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

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

"Sand." Juan says.

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

This sequence of events is repeated every week for three years. Finally, Juan does not show up one day and the guard meets him in a cantina in Mexico.

"Hey, Buddy." says the guard, "I know you are smuggling something. It is driving me crazy. It is all I think about. I can not sleep. Just between you and me, what are you smuggling?".

Juan sips his beer and says: "Bicycles". 

Bài viết unsolved mystery được biên soạn bởi giáo viên trung tâm tiếng Anh SGV.