Willow: You said, "The cow should touch me from Thursday." And... you said it wrong.
If there is a "right" way to say this, it might be "La vache devrait me toucher du jeudi." Actually, "La vache doit me toucher jeudi" ("The cow must touch me on Thursday") seems closer to the sounds Buffy was making. It doesn't make much more sense, but at least it's grammatical. Of course, only Buffy and Willow know what she meant to say.