Ive laid down AK/QQ many times, as well as KK but far less. Only time I toss KK is after a large 4 bet from a tight opponent. I never feel bad since for all the times im folding im building savings that I otherwise would have blown if i ran into aces. Example at 25nl ive got $5 in the pot PF, get 4 bet for another $10. So say i fold, i lose 5 dollars. Assume i play this hand 5 times, and each 5 times i fold. I lose $25, or 1 buy in. Now lets say that 3/5 times my opponent had aces, I would have probably gotten stacked each time. So i have saved alot of money. Now im not assuming the other 2 hands in which case i might have won, because im lazy and im heading out right now. but you get the gist of it.