[granville1]

Another studio might do it, say, Warner Brothers:

Regan to Karras: Nyeah, What’s up, Doc?
Merrin to Regan: Be SIGHwent, you wascahwy demon!
Regan (personality shift): Ah Say – Ah Say, Boy, whah dontcha stick that glorious peckeh up her ahrse!
Karras (preparing for window leap): Nuhbleegety nuhbleegety nuhbleegety – That’s all, folks!