The idea is that that liar doesn't even have
facial hair to hide his facial expression, and thus
the lie is easily recognized -- and yet is told anyway.
Note: the expression is not
bold face lie.
Saturday Night Live has had two characters that specialize in bald faced lies,
Jon Lovitz's The Pathological Liar (e.g. "Morgan
Fairchild. Yeah, that's it.") and
Kristen Wiig's Penelope the Compulsive Liar (e.g. "Mine when through the roof too, they were just really high, they went around the roof and through the roof, so high that they were all over the roof. They were higher than yours."