Tommy comes up to the Southern Irish border from the North on his bicycle. He has two large bags over his shoulders. A guardai stops him and says, "What's in the bags?"

"Sand," answered Tommy

The guardai says, "We'll just see about that. Get off the bike."

The guardai takes the bags and rips them apart; he empties them out and finds nothing in them but sand. He detains Tommy overnight and has the sand analyzed, only to discover that there is nothing but pure sand in the bags. The guardai releases Tommy, puts the sand into new bags, lifts them onto Tommy's shoulders and lets him cross the border.

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

"Sand," says Tommy

The guardai does his thorough examination and discovers that the bags contain nothing but sand. He gives the sand back to Tommy and he crosses the border on his bicycle.

This sequence of events repeats every day for three months. Then one day, Tommy doesn't show up. The guardai meets up with him in a cafe in the South.

"Hey, Tommy," the guardai says, "I know you're 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?"

"Bicycles," says Tommy.