Zahavasdad, there is one about a fish store that advertised that its fish never ate chametz. A woman phoned and asked what they ate. The owner replied that they ate smaller fish. She asked if they ate them in the water. When he said “Of course” she told him that she was sorry but she was makpid on gebruchts.
I myself once saw a package of freezer bags that was labelled “glatt”. They were very smooth bags.