<p>I have heard that it is not proper for a non-Cadet (even a parent) to use the term yuk. This is because non-Cadets have not earned the right to do so.</p>
<p>The cow story goes like this. In days gone by, Cadets were not allowed to leave until the summer prior to the Junior year. As travel was not as efficient as it is now and the primary mode of transportation to West Point was by train, the Cadets would return via the train station by the Hudson River down hill from the Plain. At that time, Cadets were required to travel in their uniforms. Seeing as it was summer the proper dress of the day was the white summer uniform. As the Cadets returned or wandered in over a period of days, they must have looked like cows coming over the hill and across the Plain to the barracks in their white uniforms. Hence, the nickname of Cow.</p>