Aantioch_Infernum/_module/nss/random_drop.nss

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

    while (GetIsObjectValid(oItem))
    {
     // if item set to droppable it will 100% drop
     if (GetDroppableFlag(oItem)== TRUE)
     {
      SetDroppableFlag(oItem, TRUE);
     }
     //10% chance of item in inventory being droppable if not marked droppable
     int bDroppable=d100()>90;

    SetDroppableFlag(oItem, bDroppable);
    oItem = GetNextItemInInventory(oNPC);
    }
}