Unintelligent Monster Rampage Chart (d12)
1 - Monster loses interest in party, leaves/retreats
2-4 - Monster is confused, no action this turn
5-8 - Monster targets random foe, roll d8 for direction of travel
9-12 - Monster attacks same target as last round, even if target already dead
Obviously these results won't work in every situation (like pretty much every random table), but I like the intent. Sometimes really dumb monsters decide they're not hungry enough to bother fighting a well-armed party, sometimes they lash out randomly, sometimes they stop to chew on the dead guy and sometimes they just don't know what to do.