Does oatmeal count? If not, my favourites are cinnamon toast crunch and cheerios. Cinnamon toast crunch does make some odd commercials nowadays. I remember a few years ago all they had was a chef, but now they have those delicious squares eating each other.
Reese's Pieces is the best oh and by the way I saw this on Tosh.O With the lucky charms cereal this is called the unlucky challenge where you have to take out all the marshmallows and just eat that nasty dry crap