The Mystery of Houdini Water Torture 

 Show a small block with a picture of Houdini on it and put it in a clear tube.
Pour water into the tube, until Houdini is all the way SUBMERGED..
The tube is covered with a borrowed handkerchief. 

After a few magic words the handkerchief is removed and Houdini has magically DISAPPEARDED!!
Then he appears from inside your pocket.

The Apparatus stands roughly 12 inches high.