Um, this is the subliminal image of the Sumerian demon who possesses Regan in THE EXORCIST, seen for a couple frames at a time here and there in the film. He was played by Eileen Dietz (http://www.imdb.com/name/nm0226326/). Here's a pic:
"she was rubbing her buttocks against the cash-machine when the SWAT team finally arrived,
a man with a megaphone said, 'COME UP WITH YOUR HANDS OUT IMMEDIATELY!',
she said, 'EAT SHIT, ASSHOLES!' and fired two shots,
she was gunned down in a typical display of sudden and decisive force."
alice donut used to rule. excellent live shows. i didn't know they were still around.