This is a strange one. If your face or likeness was on a box of cereal and it was therefore used by the cereal company to sell its product, don't you think that either you or one of your friends would notice this and point it out to you? Especially if it is a major brand cereal?
This is the story of Russell Christoff, who unbeknownst to him became the face of Taster's Choice Instant Coffee in 1998. Back in 1986 when he was modeling, Christoff posed for pictures that showed him looking longingly at a cup of coffee. He entered into an agreement with Nestlé so that they could use the photos for some coffee to be sold in Canada only. That was the extent of the agreement.
Fast forward to 1998, and Nestlé decides to "change the face" if you will of Taster's Choice Instant Coffee, taking off the present visage and putting on a new one. While looking for the appropriate face of the future, a Nestlé employee found Christoff's photos in the archives, and the company decided to use one of them.