[Nichlemn]

Well, if you're in a 5 way allin with A[img]/images/graemlins/spade.gif[/img]A[img]/images/graemlins/club.gif[/img] and you know your opponents have something like:

A[img]/images/graemlins/diamond.gif[/img]A[img]/images/graemlins/heart.gif[/img]
K[img]/images/graemlins/diamond.gif[/img]K[img]/images/graemlins/heart.gif[/img]
T[img]/images/graemlins/spade.gif[/img]9[img]/images/graemlins/spade.gif[/img]
6[img]/images/graemlins/club.gif[/img]5[img]/images/graemlins/club.gif[/img]

... you only have 18.5% equity in a 5 way pot and should fold. Of course, if you were able to know this, you can probably see everyone else's hole cards and have such an enormous edge you should fold with much greater equity.

Without such a contrived scenario, you could possibly warrant folding Aces preflop if:

a) A multiway allin if you knew one player was incredibly tight and would *never* go allin without the two remaining Aces, so the call may be +EV but not by a significant amount, and you think you have enough of an edge to pass this up.
b) Tournament equity situations, e.g. satellite bubble, mass allin where folding would guarantee you a high payout.