The suspicious-looking man drove up to the border, where he was greeted by a sentry. When the guard looked in the trunk, he was surprised to find six sacks bulging at the seams.
"What's in here?" he asked.
"Dirt," the driver replied.
"Take them out," the guard instructed. "I want to check them."
Obliging, the man removed the bags, and sure enough, each one of them contained nothing but dirt. Reluctantly, the guard let him go.
A week later the man came back, and once again, the sentry looked in the truck.
"What's in the bags this time?" he asked.
"Dirt, more dirt." said the man.
Not believing him, the guard checked the sacks and, once again, he found nothing but soil.
The same thing happened every week for six months, and it finally became so frustrating to the guard that he quit and became a bartender. Then one night, the suspicious-looking fellow happened to stop by for a drink. Hurrying over to him, the former guard said, "Listen, pal, drinks are on the house tonight if you'll do me a favor: Just tell me what the hell you were smuggling all that time."
Grinning broadly, the man leaned close to the bartender's ear and whispered, "Cars."