As well as being one of the most unintentionally amusing-sounding things you can do to a foodstuff, spatchcocking is a very good way of making meat easy to portion and quicker to cook. It's also not nearly as complicated as you might have been led to believe.
All you need to do is lay the chicken breast-side down. Make a cut with a pair of shears from the front cavity all along one side of the backbone, then do the same on the other side, effectively cutting the whole spine out.
Turn the bird over and flatten it out until you hear a "crack". You can then, if you want, secure this with skewers placed through the meat in an X shape, from legs to opposite wings.