+1
Damn! There are some good ones there.
Actually, I have two.
One is from "Lair of the White Worm," when Lady Sylvia Marsh (Amanda Donohoe) chomps down on the johnson of Kevin (Chris Pitt), the boy scout in the film, after she has just given him his first taste of oral sex. Freeze on the first frame of his reaction to her bite. Darn! I don't think I have ever seen anybody open their mouth that wide. Not at least, since the days of Joe. E. Brown.
The second is from the film "Zenobia." I don't think I've ever seen a better double take, then the one that Harry Langdon gets off in that film, from hearing something that Oliver Hardy says to him.