captain howdy is
the name of the scary subliminal pop up face that is in the original Exorcist film.
(although I'm sure you've found that now)
(
HappyToast Groat froth,
Thu 1 Jun 2006, 9:49,
archived)
It was the name used by the spirit that
Regan was contacting via the ouija board which eventually possessed her.
(
Afinkawan Yes I can hear you Clem Fandango,
Thu 1 Jun 2006, 9:57,
archived)