The RATIONAL fear of clowns. Commonly and justifiably used to describe one's fear and disgust with yellow- or green-toothed humans, hiding behind white face paint and other heavy makeup.
Poncho: Hey daddy, can we go to the circus?
Daddy Mark: Sure, as long as we stay away from those creepy and disgusting clowns!
Poncho: Oh, of course, daddy. I'm afraid of them!
Daddy Mark: Yes, son. We both have, "Clownophobia!"