It would depend on the situation, close to the Bubble I suppose I could possibly fold K/K after all in a Tournament with a large enough prize pool I have folded A/A in this situation, and I was proven right to do so as the Bubble boy went out, leaving me in the money and the person who took him out would have beaten me as well.
Early on in a MTT If I was struggling then I would possibly call an all-in with any Pocket pair, I once heard 2 players talking about how one had folded Pocket Deuces pre-flop, and had he called he would have won the last hand, I said "Boy if I had Deuces I would have been all-in." They both laughed and I was dealt Pocket 4s in the very next hand. I shoved and one asked "did you get your Deuces?"
I just replied "Oh this hand is better than Deuces" I got one caller and I turned my 4/4 over and said "this is twice as good" I beat the caller who had A/K suited and I took a well needed double up. Even the caller was laughing after I beat him but at the end of the game I had some fun, and to me that is reason why I play Poker!
When the fun Stops, STOP!