Bran Flakes is a brand of cereal featured on a TV ad in the episode: As Seen on TV. The cereal obviously has bran in it, because of the "Bran" in its name.
Bran Flakes is featured when an old fish watches the cereal's commercial on TV. He mistakes SpongeBob for a cereal box from the commercial, even saying "what a nice cereal box".
Boxing and Taste
It is unknown what the food tastes like, but it is presumed that it is for older people, and it is identical to normal bran. The Boxing is yellow, and has pictures of the food on it. Nutritional info and other info is on the right side of the box. For taste in As Seen on TV it is mentend to have a bold new taste.