I did a search in google "atlantica online feast exploit" and it poped up its little summary of forums and it included the un-edited version from the official forums. This is the part I got:
1 day ago – If you click a feast and then before clicking to start it on the menu, move the ... Forums > · ATLANTICA ONLINE · Palatino Plaza; Feast exploit ...
So my guess is for the exploit is you just need to move the feast into one of your permanent bags where it should be safe from being used. At least its worth a shot.