In a cash game, call. As others have pointed out, there are circumstances in tournament poker where it is a fold. In fact, it is sometimes correct to fold AA preflop in a tournament. There are free tools like equilab that can help you answer this question, and many others like it. Back to the question; from an EV perspective, it is a call in a cash game no matter the conditions since you are a favorite to win the hand. However, if your
bankroll is on the line, it's probably a fold. If someone open shoves AK and you have QQ, you may consider a fold if losing the hand will cause you to tilt, or make you play badly. Since you have nothing invested in the pot, the variance will be higher. There may be other factors than strictly EV that influence your decision making process, although rare.
For example, sometimes you have to consider the rake. We can never put our opponent on a single hand, and instead put them on a range of
hands. If you have QQ, and your opponent has the range {TT+,AKs,AKo}, then you are a 52% favorite against this range, and should call an all in. However, because of high rake at lower stakes (5% and higher), this will be -EV, or at best break even.
-vulpix