Not a real word. It's octopuses, you jerks! Or, alternatively, octopii.
Actually it depends how you look at it. In any part of society where discussions of the creature in question were limited to biologists then the correct word would be the more scientific octopodes. In society where the creature is frequently refered to and hence has its name considered a non-specialised part of the vocabulary then yes octopuses would be a valid word.
