void main()
{
    object oNPC = OBJECT_SELF;
    object oItem = GetFirstItemInInventory(oNPC);

    while (GetIsObjectValid(oItem))
     {
      if (GetDroppableFlag(oItem) == TRUE)
     {
      //items already set as droppable should stay that way
      SetLocalInt (oItem, "droppable", 1);
      GetNextItemInInventory(oNPC);
     }
      if (GetLocalInt(oItem, "droppable") == FALSE)
     {
      //20% chance to drop item inventory not already set as droppable
      int bDroppable=d100()>80;
      SetDroppableFlag(oItem, bDroppable);
      oItem = GetNextItemInInventory(oNPC);
     }
    }
}