The new Ensign was assigned to subs, where he'd dreamed of working since a
young boy. He was trying to impress the Master Chief with his expertise learned
in Submarine School.
The Master Chief cut him off quickly and said, "Listen, 'sir', it's real
simple. Add the number of times we dive to the number of times we surface. Divide
that number by two. If the result doesn't come out even, don't open the hatch."