a/k/a Reversal Of Fortune
Stan Daniels (1934-2007) was a comedy writer and producer, best-remembered for his work on The Mary Tyler Moore Show and Taxi.
From Daniels' Wikipedia page:
Daniels' influence in comedy is noted by the joke setup credited to him ("Stan Daniels turn") wherein, "a character says something and then does an immediate 180-degree shift on what he just said," according to The Simpsons producer Al Jean. An example of this may be Tony Blair claiming that the Good Friday Agreement is not a day for soundbites, then, immediately going on to say that he, "feel[s] the hand of history on [his] shoulders."
When I was a college student, studying comedy in my spare time and going through various joke structures, I noticed this structure and labeled it the "Instant Reverse" or "Immediate Reverse."
The joke that was a real eye-opener for me is from a 1976 Mary Tyler Moore Show episode where Ted has recently auditioned to host a game show in New York. Thinking he's lost the job, and smiling through tears, he tells Mary and Murray that they are like family to him, and he could never leave this small Minneapolis TV station. It's his home.
The phone rings -- Mary answers. "Ted, it's for you. New York calling"
Ted immediately switches from tear-filled joy to deadly serious determination: "Good, maybe that's my ticket out of this dump".
The first time I saw this episode in re-runs, when I was very young, I literally laughed until my sides hurt. Baxter was a great character and Ted Knight's delivery flawless. Perhaps it was because this joke structure:
1. Heartfelt sincerity from A.
2. Influencing action.
3. A is revealed to feel completely the opposite of #1.
... was so rare at the time. It was rare - maybe that's how it ended up named after Stan Daniels. But it was not unknown.
I can think of examples from Get Smart, the 1969 British spy spoof and cult film Otley, and even 1776. There's a version as early as The Paleface (1948):
BOB HOPE: (Smugly proud of himself): "Before we go on I'd like to say a few words."
OLD-TIMER: "We better get out of here before them murderin' Injuns come back."
BOB HOPE: (suddenly realistic and unsmiling): "Those are the words."
There were some done on Daniels' later series Taxi -- one in "Tony The Boxing Manager" recycles a variant that had been used in the 1972 Burt Reynolds private-eye movie Shamus.
BURT (indignantly): "You think you can buy me??"
GANGSTER: "I'll pay you $25,000 cash."
BURT: "Congratulations. You just bought me."
And of course Cheers -- an MTM show in all but name -- would do one every episode:
FRASIER (pompously): "A psychiatrist must always be there for his patients."
(His beeper goes off)
FRASIER (grumpily sarcastic): "Great. I bet this is important..."
Eventually some sitcoms began doing 4 or 5 a show -- especially after the Frasier character made "The Pompous Guy" a fixture on sitcoms -- and weakened the effectiveness of the joke through overuse.
Too bad Daniels didn't get a royalty.
Used sparingly and in the proper situation the Immediate Reverse can get a huge laugh... and maybe it'll be my ticket out of this dump.