The actual definition of a Houdini shit is a turd that contains enough negative buoyancy to drop to the bottom of the toilet and glide it's way down far enough into the toilet's exit portal that it appears to have mysteriously disappeared or make you question whether or not you even crapped to begin with. It often times shares the characteristics of a Jesus Shit, which is the term used for turds that leave no residue on the anus.
Boy, today's Ziggy cartoon was pretty funny. Oh well...I'm done wiping so I guess it's time to stand up, flush and get back to wor- OH MY GOD! HOUDINI SHIT!