April Fool!

It is April Fools day.
The day when we all get to go around, and lie freely, as long as we follow that lie (eventually) with the words "April Fools!"
I have done my fair share of April Fools Day jokes. One year, when we had the foreign exchange student, her and I staged this elaborate argument with each other just to mess with my Mom. When she got home from work, we started yelling at each other and carrying on like crazy. We had never argued with each other, so to say she was shocked was an understatement. She came in and started in on the "now girls" speech, and we started busting up. We could not help it.
But then our fine April Fool backfired. Mom wanted us to stage a big fight with HER for when middle sister got home. My Dad was around, and recommended we NOT do this. Did we listen?
No.
So, when middle sister and her and boyfriend got to the house, we started arguing again. It was about our up coming trip to San Francisco. Foreign Exchange student and I were yelling at Mom that we didn't want to go.
Middle sister was PISSED OFF to say the least. She came in and tore into us like a lion eating a zebra. She even called us Ungrateful Bitches and then stormed out the door. While her boyfriend sat there, stunned. My Mom had to chase her out the door and explain things. My Dad simply said "I told you so".
I've also done some milder jokes. My favorite one was a few years ago, though, when I was getting my passport to go to France. I had to send away for a certified birth certificate, and I happened to get it on April Fools Day. So, I called my Mom, and started asking her "Why didn't you tell me?" I then explained to her that there was a different man listed on my birth certificate under the name of 'father'. Boy, you should have heard her sputter. It was kind of fun.
So, Happy April Fools Day. Yes, I really did buy a Jeep, that wasn't a joke. We have a favorite name in the running, but the contest is still open for any of you that want to pick one...
Tell me, either comment wise, or blog wise, what was your favorite April Fool that was either done to you, or you did to someone?