this thread is stupid, pointless and probaply will be locked soon but i found this picture what shows how you can get antigravity http://kuvaton.com/kuvei/antigravity.gif
I don't think two cats (cats because pieces of toast would be too simple) attached together will create antigravity. It's more like a propeller effect: Maybe you could work out how fast the cats need to spin in order to lift themselves http://en.wikipedia.org/wiki/Propeller#Thrust_and_torque