Looking for a safe-yet-hilarious prank to pull on your unsuspecting coworker? Imagine this: your target shows up at his desk after a 15-minute break. Everything looks normal. He begins to click an icon to bring up a program. It does nothing. Perplexed, he shifts his focus to the Start Menu. It won’t start. Believing his computer is frozen, he restarts it. Everything is the same. Just as he furiously reaches for the phone to call tech support, you let out a devious chuckle – score one point for the prankster.