It is a parody of a type of bad writing sometimes known as said-bookism, where authors keep a book of alternative words to use instead of said. Examples:
- "Yes" he muttered.
- "Yes" he whispered.
- "Yes" he roared.
- "Yes" he exclaimed.
- "Yes" he hissed.
- "Y-Y-Yes" he stuttered.
A variation is to use said, but add an adverb or other descriptor.
- "Yes" he said angrily.
- "Yes" he said with contempt.
- "Yes" he said in a low whisper.
- "Yes" he said happily.
Or, they can combine the two:
- "Yes" he hissed in a low whisper.
One or two examples in a story is acceptable. More than that and it becomes annoying. Famously, the Tom Swift series of books used them excessively. Here's a sample:
"Oh, I'm not a professor," he said quickly. "I'm a professional balloonist, parachute jumper. Give exhibitions at county fairs. Leap for life, and all that sort of thing. I guess you mean my friend. He's smart enough for a professor. Invented a lot of things. How much is the damage?"
"No professor?" cried Miss Perkman indignantly. "Why I understood from Miss Nestor that she called some one professor."
"I was referring to my friend, Mr. Swift," said Mary. "His father's a professor, anyhow, isn't he, Tom? I mean Mr. Swift!"
"I believe he has a degree, but he never uses it," was the lad's answer.
"Ha! Then I have been deceived! There is no professor present!" and the old maid drew herself up as though desirous of punishing some one. "Young ladies, for the last time, I order you to your rooms," and, with a dramatic gesture she pointed to the scuttle through which the procession had come.
"Say something, Tom — I mean Mr. Swift," appealed Mary Nestor, in a whisper, to our hero. "Can't you give some sort of a lecture? The girls are just crazy to hear about the airship, and this ogress won't let us. Say something!"
"I — I don't know what to say," stammered Tom.
So, the movie line is mocking this type of prose.
There is also a type of pun called a Tom Swifty which combines a parody of this type of prose, with a pun.
- "I arrived by parachute" Tom explained.
- "Look at my wedding ring" said Tom with abandon.
- "You must be our mysterious host" Tom guessed.
- "I'll sue you again" Tom retorted.
I thought the line might be a Tom Swifty, but I can't see a pun there.