Found this surfing around tonight, I even remember it from the "real" Hitchhikers Guide to the Galaxy
For this anti-gravity experiment we will need one cat (preferably cute) and one piece of toast buttered on one side only. Now this experiment relies on two constants, one being a cat in motion will always land on its feet. And the other being when buttered toast travels from point X to point Y, it will always land butter side down.
Once the cat and toast have been properly joined together with the butter side facing away from the fur step back and enjoy, because there is no way for this paired object to reach the ground according to our newly proven scientific laws. Think about it, if the toast were about to land buttered side down that would void the kitten from landing on its feet. However, if the kitten was to land on its paws then the buttered side of the toast wouldn't be face down on the floor. There is no conceivable way for them both to land.
There you have it, the first ever kitten n' toast anti-gravity device. Now we must work on securing them to snowboards only then will we be on to something truely great.