American Dad!, one of the best animated series you're probably not watching, has a formula that has served itself well since Season 2. The writers set up a scenario that's a spin on classic sitcom tropes. Then, in the final few moments, something totally unexpected happens that pushes the joke into wild and unexplored territories. The resolution is rarely what you know has to happen based on the set-up but it still feels satisfying because the pay-off is big laughs. There are some traditional suspense elements used for great comedic effect. The writing team is fond of Chekov's gun. This is the principle that states if you introduce a loaded gun in a play, it has to fire before the curtain falls; otherwise, you didn't need the gun at all.

On American Dad!, the gun is rarely a gun. In one episode, where Roger the alien demands a roast for his birthday then traps the Smith family in a revenge fantasy for hurting his feelings, a rare pair of scorpions are introduced during the second segment. They will eat the inside of the human body through whatever orifice they can enter. The scorpions accidentally enter Roger but then burrow their way out during the final few moments for grand comedic effect.

In another episode, the Smith family is moved to Saudi Arabia and Stan embraces total control over his wife and daughter. An early scene sees one of his new coworkers shot dead for singing in public. Out of nowhere in the final few minutes, his wife Francine rebels against his new-found authority by performing an elaborate song and dance routine that results in a death sentence.

American Dad!'s use of the Chekov's gun concept for humor usually plays out more than once. It is a very rare episode that doesn't somehow turn on a prop introduced in the first segment. It's rarer still that the first use of the prop is the only use of it. The show sets up the importance of a visual gag, puts it on the backburner, then hits you two or more times with jokes you've been waiting for the whole time.

But the formula of American Dad! really relies on the plot twist in the final few moments. The recent Lent-themed episode establishes a rather nasty conceit. The Smith family agrees to a bargain with the CIA director to break their vices. The first family member to act on their bad habits will surrender a finger for the director's collection.

Right away, the characters try to sabotage each other to save their own fingers. When those efforts fail, they fake a mass murder/suicide to convince Francine to light up a cigarette to calm down. The director demands the contract be upheld and sets up an elaborate ritual to remove the finger. Expectedly, the family decides to offer their own fingers in place of Francine's, ending the contract once and for all. The happily ever after is short-lived as Stan chops his own finger off so the family finally commits to something they agreed to do. It was totally unexpected and led to a dry joke about cartoon hands that ended the episode.

The twist in the final few moments took the ending the audience anticipated, the Smiths coming together to oppose the brutal contract, into a wild and bloody sight gag. The sight gag tied into the original conceit of the episode where no one in the family ever followed through on a promise. The expected conclusion was a twisted act of misdirection before the real ending could unfurl.

American Dad! uses this formula to attack a wide range of controversial subjects with a lot of humor. Murder, warfare, reproductive rights, education in America, helicopter parenting, gay marriage, drug abuse, and a whole lot more are turned into bizarre and unpredictable commentaries on the form of the sitcom. On other shows, you know the character is going to get their head out of the grand prize trophy by the end; on American Dad!, the person's head is removed from the trophy shortly before something completely unexpected pops up onscreen that shifts the focus to a throwaway line at the top of the episode. The result is a very funny show riffing on current events, genre fiction, and the traditional American sitcom.

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