There was nothing more frightening to me, as a child, than the soul sucking gaping faces of the Yip Yips. Of all the weird media moments in my youth, these Sesame Street aliens take the creepy-holy-mother-of-god-get-out-of-my-head cake. Their evil vacuous mouths graced TV screens everywhere in 1971 in this telephone sketch. I dare you to watch one of the clips after the jump and not feel incredibly uncomfortable or creeped out.
Especially when they start moving their mouths back and forth.