topped with beer
in place of milk
Popular concept in American Colleges/Universities, where beer flows like water and short-shelf life staples like milk are hard to find. Students at said institutions, usually out of laziness, make less and less frequent trips to grocery stores, particularly students living in dorms who are provided with meals through the university cafeteria system. Since these students have no need for (and often no capability to store or prepare) foodstuffs, only easily-preparable and spoil-free items like breakfast cereal, soda and instant ramen noodles pile up in their closets or under their beds.
Beer, the ever-present lowest common denominator among college students, quickly becomes the most convenient substance with which to soak cereal. This meal is frequently consumed the day (not morning, as the morning was spent asleep) after a wild party; it may, however, be eaten at any time.
From the name, one would suspect the most common cereal used to be any of the Cheerios-branded varieties, but in reality any cereal can be used. Most often, over-sugared cereals are used as they are the preferred variety among beer-consuming college students.