I don't think Clark ever spoke that line in the show, either ... maybe the person is confusing Lois's "Slave to concubine, is that a step down?" line with Clark's earlier, "My little ... tornado!"?
I do think that would be a funny line to include in a fanfic, though, to have Clark be teasing Lois and say, "Come here, my little concubine!" The look on her face would be priceless, LOL!
Kathy