Here are some tips for maximum prank effectiveness:
- Set the stage -- Run it on a coworker's computer when they step away from their desk, then watch their face when they come back and see it "sending emails"
- Play dumb -- Act surprised and concerned when they show you what is happening: "Oh no, is that a virus?"
- The slow reveal -- Let them panic for a moment before revealing the truth -- but do not wait too long or they might try to unplug the computer
Remember: always prank responsibly and only target people who will appreciate the joke.