This is a nice practical joke to use cautiously. Employers paying salaries for lost productivity caused by a malicious act could consider it sabotage. This could lead to disciplanary actions, dismissal, or even a law suit. Individuals who lose their precious time or lose valuable resources to a "joke" might sue you. It is funny until someone get hurt by the joke.

I know many persons with limited troubleshooting and computer skills that this prank could push over the edge emotionally. Please use your gifts to better someone's day.