I remember reading this trick, which gets the job done although not giving the audience what they were expecting. In short, open the phone book in the middle, and rip through the glue binding, so that you get 2 halves of the book: the front side, and the back side.
If you see the opened book from the bottom, it looks like this:
____ ____
/____\/____\
^^
\-- rip through here.
It's still ripping the phone book in half, and no ovens or training needed. Maybe it will impress chicks too. (I'm thinking more of chicks who prefer the brainy over equiped-with-clever-tricks the macho guy-types. :)