In the 70's these guys got busted in NYC for doing this.
They would go into a grocery store and place on the shelf boxes of ceral they had inserted a vaction prize voucher.
The people would phone the buisness on the voucher and claim a free round trip all expenses paid trip to bogata columbia. They would meet up with the friendly organzers and when their trip was done a variety of souvenirs , filled with coke, was given to them as a gift to take home. All of them always made it through customs.
At home the souvenirs would be stolen from the "courtesy limo" ride to a facility where pictures were taken of the happy couple after their free vacation. It was part of the contract.
At the same time they were told that they must have forgot their souveniers for they were notified of this, and they were being mailed to them .
Any protests by the people was fluffed off i guess.
Anyway this was just one of these dealers way of evading customs and eventually they were busted.