You're standing in your cubicle, feeling pretty happy with yourself, when somebody sticks their head into your cubicle.
"Hey, have you seen Roy?" the person sticking his head into your cubicle asked.
"Not since yesterday, when we both left work," you answer. "Why?"
"Weirdest thing," the guy replies. "I stuck my head into his cubicle to ask him a question, but he wasn't there. His clothes were, though. I mean, all his clothes. Even his underwear!"
"Well, a naked Roy shouldn't be too hard to find. I'll go help you find him," you answer.
As you exit your cubicle, you do indeed find Roy, though you were unaware of it. Roy had been the one stealing your coffee. But he had drunk so much of the special coffee, that he had shrunk out of his clothes down to a quarter of an inch in height!
Roy had somehow managed to make it to your cubicle, looking for help, and was rewarded for his efforts by you stepping on him, instantly killing him. A few minutes later, you scrape him off the bottom of your shoe, never knowing that was the remains of a coworker.
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Epilogue:
The mystery of Roy's disappearance is never solved. The working theory is that he embezzled a large amount of money from the company, but did it in such a way that, even to this day, the theft was never detected. Roy then took his ill-gotten loot and disappeared to a tropical island, never to be heard from again.
With Roy gone, you begin a rapid succession of promotions. It appears that Roy was your chief detractor, undercutting you and taking credit for your successes at every turn.
Thirty years from the day you literally stepped on Roy, you become president of the company. You've had a good personal and professional life.