During basic training, our drill sergeant asked for a show of hands of all Jewish personnel. Six of us tentatively raised our hands. Much to our relief, we were given the day off for Rosh Hashanah.
A few days later in anticipation of Yom Kippur, the drill sergeant again asked for all Jewish personnel to ID themselves. This time, every soldier raised his hand. "Only the personnel who were Jewish last week can be Jewish this week," declared the sergeant.