This contest involved matching game cards that were obtained in packages of cheese. There was one grand prize, a minivan, which was to be awarded, however a printing error (of course!) resulted in about 2 million packages of cheese with winning game cards. Kraft responded by canceling the contest, they were of course sued and ultimately paid out $10 million.
There are several newspapers that have published stories on this: Herald-Journal and The Spokesman-Review.
