A particular product from one of our customers was repeatedly targeted by shoplifters. The small package was readily available from several different retail outlets and so when a suspected shoplifter was caught, it was difficult for "ownership" of the product to be confirmed.
Whilst we cannot for obvious reasons reveal the exact details of the solution we produced, the end result was both hard to spot and difficult to locate on the product. Prosecutions followed and the project was regarded as a success.