April Fool's Day

There is a time in life when toys like whoopee cushions, fart machines and things which generally appeal to man's baser instincts stops being funny. I'll let you know when I reach that point in my life. Sorry, but seeing people fall = funny. Thus, I have an appreciation for April Fools Day. I'm terrible at pulling off pranks though, for two reasons:

1. When I know whats coming I start smirking like an idiot. Nothing puts people on alert like when someone trying to pull a prank off has a shit-eating grin on their face before you sit down. This is also why I suck at keeping secrets.
2. I don't like to single people out. There's nothing funny about just getting one person. All you're doing there is just picking on them and that's never funny, it's just mean.

Therefore any prank I'm going to enjoy needs to be one that can be done without having to be directly sitting there and also clever enough to get several people to fall for it. The best one I've ever heard of came from my father, who's co-worker pulled it off (those clever Harvard people):

He made up a very officially-looking document that stated a new upgrade had been made to the copy machine, which had made it voice activated. All the user had to do now, the paper said, was state in a clear voice the number of copies that they needed and say "copy." He had even gone the extra step of laminating the paper to make it look even more official. He then put the document on the copy machine (his cube was right next to it), sat back and enjoyed a day full of people looking like idiots as they tried to get the printer to listen to them. "Four. Copy.... FOUR. Copy. COPY. COPY. COPY!!"

Simple. Silly. Effective. Brilliant.
That, my friends, is how you pull of an April Fool's Day Joke.