Disproportionate Retribution / Family Guy

Peter: And that nice chicken out there gave me a coupon.
Store Clerk: I'm sorry. This is expired.
(Peter turns to the Giant Chicken)
Peter: You SON OF A...
(cue a brawl of epic proportions)

Disproportionate Retribution examples in Family Guy.

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• In the series premiere, the family is watching an episode of The Brady Bunch. In the episode, Greg is forced to spend four hours in a snake pit for smoking, while Jan, who alerted the parents to this and showed smug satisfaction in seeing Greg's punishment, is ordered to spend an entire day in a chamber of fire for tattling.
• Peter playfully tickles Lois, who tells him to stop while laughing. When he keeps going, she breaks his nose with a frying pan. Peter lampshades it:
  Peter: I tickle you, you hit me on the head with a frying pan?!
  Lois: I told you to stop.
  Peter: I taste blood!
  Lois: Well, there's a lot of it.
• Stewie beats Brian to a bloody pulp, including using a flamethrower on him, because Brian failed to repay a debt of 50 dollars to him.
• In "Screwed the Pooch", Brian stuffs animal snacks in Stewie's pockets and causes the animals to attack him as they attempt to eat the snacks... because Stewie told him to shut up.
• Peter's violent feud with Ernie the Giant Chicken is because Ernie gave him a coupon that turned out to be bad. And after they finally strike a truce, they almost immediately resume fighting because Ernie refuses to let Peter pick up the check at a restaurant.
• "The Tan Aquatic with Steve Zissou": Peter resorts to thrashing Kyle simply because he called him a "poopnose". To Peter's credit, he does try to be civil with him and ignore his insults, but Kyle refuses to let up.
• A crowd attacks Brian and levels death threats at the family over a racist joke Brian tweeted out in "The D in Apartment 23".
• Quagmire attacks Brian at the Griffin's home after finding out the latter, unknowingly, had sex with his newly transgender dad.
• In "Tiegs for Two", Brian screws up a date and blames Quagmire's dating advice, though the latter labels him a loser in response. The next day, Quagmire finds Brian hooked up with Cheryl Tiegs, the love of his life and the source of a lot of his inner demons, complete with the dog gloating and flipping the bird.
• In "Killer Queen", a former hot dog eating champion attempts to strangle Chris to death just because Chris beat him in the competition, which he feels had caused him to lose his honor.
• An early Cutaway Gag has Old Yeller about to be put down for accidentally deleting a message on the answering machine.
• In "Halloween on Spooner Street", Lois sets out to retrieve the candy Justin had stolen from Stewie. After she gets Justin's mom to return the candy, she extorts the woman, demanding Justin's own candy and $40. Though Justin's mom tells her she doesn't have $40, Lois declares she'll be back for $80, and takes their welcome mat. Even Stewie is a little scared by this.
• A cutaway gag of a German bedtime story features a mother cutting off her son's thumbs simply because he wouldn't stop sucking them (which is based on an actual story from Struwwelpeter).
• In "Girl Internetted", while Peter is at a convention, a man gets him kicked out, then kidnaps him and nearly cuts his arm off with a chainsaw. All because Peter said he had a weird ponytail. Even worse, Peter deliberately did it to get views on his Instagram; he just didn't count on the guy being a psycho.
• In one episode, Mayor West attacks the pizza delivery man with a cat launcher for giving him Canadian bacon on his pizza instead of regular bacon.