Live you are gonna run KK into AA for sure, the only way i find a fold live would be to have a deadset read on my opponent. Ive done it twice and was easily right twice but i knew my villan very well. Online, i think its much more difficult to fold it.
I folded KK a few months ago in an online tournament because it was the bubble, im 2nd stack and the big stack just open shoves - i didnt put him on AA by any means, he had been doing this alot, the fact is i had plenty of chips and i didn't have to risk anything on the bubble like that. Once the we're in the money, then i attack him back.
In the end, the BB called the open raiser had A9 offsuit and flops A97 so again, glad i folded the kings tho i knew i likely had him crushed pre. I made the money, and cashed decently in the tourni.