Diablo, you're making a good solid point as well, but there are just sometimes when you know it'll benefit you more not play them. I've only ever not played it once, not KK though, I think it was AA. And that was in a situation like StackEmUp was explaining. Final table, couple people already all-in. If you call, you MIGHT win, but you're now down to, what is it, like 60% chance of winning. I believe I made the right decision because a few people were knocked out and made some more money.
On the other hand, some people are saying they'd fold them on the bubble. Forget that, usually the money you'll hit just inside the bubble is barely what you payed to enter the tourney, and you shouldn't be playing a tourney where you don't mind losing the money you used to buy-in. Being too worried to lose that money is going to restrict you from playing your best game. If you get aces or kings on the bubble, who cares if you don't make it to the money. You've got a substantial chance here to make your stack even higher, which will allow you to make it even farther into the money. If you lose, you lose. It doesn't happen often but it has to sometimes.
In conclusion, I believe the only time you should your kings or aces is when you're definitely going to be making an extra amount of money at a final table. (And I'm not talking like an extra $10, I'm talking much bigger. If you're only going to make an extra $10 bucks by not calling, call and try to go even bigger. If you're going to be making $100 more by not calling, don't call.
As for the guy who said he'll never fold AK, you've got a lot to learn. You'll never go far in poker without folding those. I've folded them plenty of times. You'll win more than you'll lose if you fold them when you need too. Someone with 2-2 still has a favorite over you. It's a strong hand, but not a never-fold strong hand. If someone's betting into you big, most likely they've got some high pockets. You should be folding.