Cadet Regulations Article 5-G-1-01-a-5: "The Academy Mission plaque and the picture/paining authorized in G-2-33 are the only articles that may be affixed to the bulkhead in a room."
G-2-33: "...Cadets may also hang on the bulkhead of their rooms a single framed picture/painting (not to exceed 24''x24'' size and a frame not to exceed 3'' in width and a max weight of 7lbs) of professional and mature taste per occupant. The picture/painting will be affixed to the bulkhead by either "blue-tack" or a removable adhesive-type hook; it will hang approximately halfway between the overhead and the top of the rack and will be centered on the rack itself. All pictures and/or paintings may be subject to approval by the Company Executive Officer, to whom all questions regarding the appropriateness of any picture/painting will be directed."
So in short, no they can't hang one.