Sorry but you can fold it in rare circumstances. Look up on youtube Phil Helmuth with AA vs KK vs AA. The woman with AA (cant remember who it was) starts cheering and running around when she gets called by Helmuth after reraising the KK. The KK thinks for about 30 seconds then calls. I mean. You raise. Someone after you pushes, then Phil Helmuth pushes, and the woman who pushed starts cheering. What do you think she has?
Online, early on though, repush all in. If someone has aces, it's a cold deck, and you where meant to lose. It happens. Same goes for flopping bottom or middle set and thinking you should fold in case someone has top set. Its a cold deck. Anyone who thinks you should fold a flopped set in case its against top set is an idiot and plays way way way to tight!