Heh don't know if I've told this one before but my best April 1st prank was when I was a kid. I had an excellent idea in the morning after I was fooled by my parents. I drew a "treasure map" for my little brother and wrote a letter telling that a great treasure was hidden in our house. Then I put both the map and the letter to an envelope and wrote my brother's name on it. I didn't tell anyone about my plans and hurried to place my letter to our mail box before anyone picks up the paper.
My brother was too young to even know how to read but luckily my mother read the letter to him (thanks mom, my best ally) and he could figure out the map by himself. He searched and searched and finally found the position where I had hidden just another clue instead of a treasure. He spent several hours searching all the clues and my mother reading them to him. Sometimes I had to go to my room because I couldn't hold my laughter :lol:. After ~10 clues he finally found the last paper saying "April's fools!"... Oh boy was he disappointed. And I burst laughing like a maniac, causing him almost cry. Later in the evening I let him prank me back because I started feeling sorry...
Maybe that's why my brother still tries to April's fool me every year...