hoodini poop 

When you poop and it look completely soild but when you flush it turns in to a poop cloud and disappears

Man I have been taking so much laxitives the my poop is like a hoodini poop

hoodini poop by It-happens January 30, 2015

Houdini poop 

When you take a large poop but when you look at the toilet it is not there.

Guy: "shit man I took a dump but when I looked it was gone!"
Guy 2: "looks like you had a houdini poop."

Houdini poop by Faceplant307 December 21, 2015