I don't know if this counts as successful, but I once hid a fart machine behind the shomen. Every time the teacher bowed I pushed the button. But later after I put the control on the side of the mat he took it and pushed it every time he called me up to be uke. Then he made comments like "no more Taco Bell for Rose."
LOL, if that woulden't get me killed, I would so play that prank.