Cowznofski is a runningin-joke heavily used in the early years of MAD magazine, usually as a character's last name, often with the first name "Melvin", occasionally "Lance" or "Irving." Its Eastern European feel was a perfect fit for the New YorkJewish style of the magazine. It is also one of the units in the magazine's joke Potrzebie unit system created by Donald E. Knuth, in which it is the equivalent of a year.
A character similar to Alfred E. Neuman named Melvin Cowznofski – a tall man with a large, broad nose, receding hair, glasses, and an obvious small brain – appeared a number of times in the magazine in the 1950s. In one issue he is described as an editor of Collier's Magazine, and manufacturer of souvenirs for the Brooklyn Dodgers. (Both Collier's and the Brooklyn Dodgers were defunct by then.) He was said to be "barred from 48 states (and Alaska will be voting any minute)"; Hawaii had not yet achieved statehood. Still, he "held a high position in our country, living atop Mt. Whitney."
Moxie Cowznofski was Neuman's girlfriend for a period in the 1950s. 
^"The genesis of Alfred E. Neuman, a.k.a. Melvin Cowznofski". Chicago Tribune. May 4, 1980. pp. G48. "No one really knows just where the kid came from. That face has been around since about the turn of the century, and several people claimed to be the creator of the now-familiar gap-toothed idiot. ..."