This video of a live Tickle Me Elmo doll going up in flames is easily the most disturbing thing I've seen all month -- it writhes and thrashes and laughes with mad glee, begging you to "stop it" while its charred body dances with red flame. This is some deeply twisted stuff. Link (Thanks, Fipi Lele!)
Update: An anonymous puppeteer writes, "When I was working on 'Elmo in Grouchland' they were using a radio control Elmo for a couple of scenes. These RC puppets used to be prone to all sorts of problems. They'd go into seizures if a cab went by broadcasting at the same frequency. So, we were all used to the puppets suddenly freaking out and twitching. Until Elmo caught on fire. He was hanging from a basket twelve feet over the stage floor, and went into the twitching routine. Then smoke started pouring out of his neck. They cut the power and hit him with a fire extinguisher so fast you'd think he was a real person. It turns out that some of his fur had gotten caught in a servo. "