From a USNA Alumni website:
Item: Midshipmen who have physical education wear whiteworks (the traditional white “middie blouse” [sailor’s jumper] and bell-bottoms) over their gym gear to classes for the morning or afternoon that they have P.E. One day a tourist in the yard stopped a Midshipman and asked him why most of the mids were in blue uniforms but some of them were in white. He looked at her and replied “Lady, the ones in white are virgins!”
Item: Midshipmen who have physical education wear whiteworks (the traditional white “middie blouse” [sailor’s jumper] and bell-bottoms) over their gym gear to classes for the morning or afternoon that they have P.E. One day a tourist in the yard stopped a Midshipman and asked him why most of the mids were in blue uniforms but some of them were in white. He looked at her and replied “Lady, the ones in white are virgins!”