Or P.O.S.T.L.I.V.E.B.L.O.G.G.I.N.G. for short.
To follow these step by step instructions you will need:
One office-wide shared screensaver
One sometimes paranoid co-worker with limited computer literacy
10:00: Use Paint to produce black rectangle with the following words written on it in red: "Please be patient. Currently deleting your files. Time remaining: 7 minutes."
11:00: While co-worker is out for a cigarette, replace normal cycle of pictures for screensaver with previously made rectangle.
11:02: Tell fellow co-worker about the joke.
11:10: Why hasn't he seen it?
11:30: WHY ISN'T IT WORKING?
12:00: Sneak into his office, reset his screensaver timing from 10 minutes to 1.
12:01.30: HOW CAN HE POSSIBLY NOT HAVE SEEN IT?
12:05: Casually walk into his office, casually ask about the thing on his screen. Get him to look up and read it. Walk over, try a few things, then move the mouse and it disappears. "Hmm, that's odd. Well, I guess it's gone. Tell me if it happens again."
12:05.15: Scramble back to your desk and remove his files from the shared folder.
12:07: "My files are gone!"
12:08: Tell him you'll look into it. Let him stew for a bit.
12:10: Co-worker/accomplice overacts it and almost gives it away.
12:15: Start referring to the problem as "your virus." Introduce the "virus" to your computer.
12:15.05: Catch him on his run to the phone to call tech support and tell him "April Fools."
Given the slow start, it turned out pretty well.
Also, last night between 9:30 and 11 I went from stone sober to so drunk I thought it was a good idea to climb on top of a friend's Toyota van. Maybe I should've post-live blogged that story instead.