One day while taking dictation, she noticed his fly open.

When leaving the room she said, "Mr. Smith, your barracks door is open."

He did not understand her remark, but later on he happened to look down and
saw that his zipper was open. He decided to have some fun with his secretary.

Calling her in he asked, "By the way, Miss Jones, when you saw my
barracks door open this morning, did you notice a soldier standing at attention?"