From an ex-USMC colonel friend of mine:
A U.S. Marine colonel was about to start the morning briefing to his staff. While waiting for the coffee machine to finish brewing, the colonel decided to pose a question to all assembled. He explained that his wife had been a bit frisky the night before and he failed to get his usual amount of sound sleep. He posed the question of just how much of sex was "work" and how much of it was "pleasure"?
A major chimed in with 75%-25% in favor of work.
A captain said it was 50%-50%.
A lieutenant responded with 25%-75% in favor of pleasure, depending upon his state of inebriation at the time.
There being no consensus, the colonel turned to the PFC who was in charge of making the coffee and asked for his opinion?
Without any hesitation, the young PFC responded, "Sir, it has to be 100% pleasure.
The colonel was surprised and as you might guess, asked why?
"Well, sir, if there was any work involved, the officers would have me doing it for them."
The room fell silent.