For her third birthday party, I taught my daughter to sing "blue makes the boys poo" as the previously unknown second verse of the more common "pink makes the boys wink" song.
Why? To wind her mother up of course. It worked perfectly: she sung it at her party in front of all her friends (who thought it was hilarious) and their mothers (who also thought it was hilarious but suppressed their laughter so as to not encourage their daughters) and her mum (who was mortified). Singing lessons have been canceled for this years birthday.
More recently, Steve Yegge, a developer at Google, wound up the normally hebetudinous software development world with his witty p*ss take of agile "methodologies". Just in case you didn't get it (I didn't at first) he's kidding. It's an April fools joke, just 6 months late ... or 6 months early, depending on your preferred methodology.
Great way to get his blog traffic up too! It's just a pity that I can't add his weblog to my (much improved) Google Reader account because it has stopped working today.