The Null Device
A psychological experiment recently performed in Scotland has shown that people are sexually attracted to sex-changed images of themselves, without realising that the images were of themselves.
A few prank-related items: Via Jimbob, an interview with SubGenius Paul Mavrides from the Re/Search Pranks book (which is recommended; in particular, the Boyd Rice interview is most inspiring).
A SubGenius friend named Janor was watching a TV Preach-a-Thon. The preacher was taking phone calls from people who needed "the healing help of the Lord," so Janor put on his "hick" accent and called him up, impersonating a totally paranoid man who had been driven crazy by Jesus. He said something like, "Jesus scares me to death -- I'm sure Jesus is the Devil in disguise. Isn't Jesus like a vampire, because he rose from the dead and all his followers are supposed to drink blood and eat flesh?" The host immediately got sucked in, saying, "No, son! You're confused!" Janor continued (in a quavering voice), "I tried to go to church, but they said I was possessed by the Devil. Then they stood around in a circle and _beat_ me with their Bibles, and now I can't even go _near_ a Bible! I get scared just thinking about it!" He wasted the preacher's entire show taking in circles. The more the guy tried to help him, the worse it got!
And then, via the Law of the Playground site featured here earlier, there's an account of a prank performed on a Melbourne train line sometime in the 1970s; it reads like something out of How To Make Trouble and Influence People.