Bald-faced or bold-faced? This is one of those commonly flubbed phrases in which both versions sound a whole lot like one another. In fact, they're both correct; they just happen to have two slightly different meanings.
A bald-faced lie -- or barefaced, as it's often called in England -- means one that is undisguised and clearly untrue. A bold-faced lie, on the other hand, is one that is impudent or disrespectful [source: Grammarphobia]. Many lies would fall under both categories.