Well, as far as my knowledge goes, (and I`m sure I can be corrected by a Kiwi on here), the haka is supposed to be a war dance, a challenge set out, almost a call to arms. So it actually begs to be responded to. Not by making a mockery of one of the most awesome sights in world rugby, but do face up to it, show that you`re not afraid of the physical challenge being thrown at you.
Earn your opponent`s respect by facing up to it, and not backing down. Then do exactly the same on the field- don`t back down an inch, scrap like hell if you`re in a corner, and throw everything, including the kitchen sink, at the AB`s. If you front up, both at the haka and at the breakdown, you`ll be a helluva long way towards getting respect from them, and also towards being competitive.