[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/7f22.png]]
Episode - 7F22\\
First Aired - 7/11/1991

Mr. Burns is in dire need of a blood transfusion, and Bart is the only one who has the same rare blood type as Mr. Burns, so Homer forces Bart to donate under the impression that the family will get a buttload of cash for the generous deed. But when all they get is a "Thank you" card, Homer writes a strongly-worded letter -- which Bart ends up sending after Marge talks Homer out of putting it in the mail.

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!! This episode provides examples of:

* AndroclesLion: Homer tells a variant of the classic story (he throws in Hercules and claims it's from Literature/TheBible) to convince Bart to donate blood.
* DecoyProtagonist: Bart. Homer takes over after Burns' half-hearted thank you to Bart outrages him, and the only significant thing Bart does for the rest of the episode besides follow Homer is make a prank call to Moe's Tavern for "Mike Rotch."
* DramaticThunder: Happens the moment Mr Burns calls Smithers a "Judas".
* DrowningMySorrows: Homer does this after being fired for his letter to Burns. Barney reminds him that he should not get drunk to forget but only to improve his social skills.
* ImposterForgotOneDetail: When Homer tries to get the letter straight from the post office.
-->'''Homer:''' Hello, my name is Mr. Burns. I beleive you have a letter for me.
-->'''Clerk:''' Okay, Mr. Burns. Uh, what's your first name.
-->'''Homer:''' (''beat'') I don't know.
* IWillShowYouX: Homer's "I'll show you MAD IN THE MORNING!"
* KarmicJackpot: Homer becomes enraged when Bart's donation of blood to Mr Burns fails to result in this trope and writes an angry letter. In a SpoofAesop, Mr. Burn is initially furious and prepared to make the Simpsons suffer, but Smithers points out that Bart saved his life, and as a reward gets the family a massive Olmec monument, which is [[ContinuityNod seen in their basement in later episodes]].
* LostAesop: Discussed in the end, when the Simpsons try to figure out a moral to the story (such as "No good deed goes unrewarded" or "The squeaky wheel gets the grease") and then realize that something that occurred contradicts the moral. They eventually conclude that "it was just a bunch of stuff that happened."
* LoveLetterLunacy: A Hate Letter Lunacy unfolds when Bart accidentally sends off the StronglyWordedLetter to Mr Burns.
* LovingDetails: Marge demonstrates an intimate knowledge of not just her husband but her whole family, including Homer's blood type and earmuff size, Lisa's ring and shoe sizes, and Bart's number of teeth and allergies.
* PrankCall: Bart calls Moe to ask for "Mike Roach".
* StoppedReadingTooSoon: Homer writes an angry letter to Mr. Burns, which starts out as a fake thank you note. Mr. Burns at first reads the thank you part, and is deeply touched, until he later discovers the following sentences.
-->Dear Mr. Burns... I'm so glad you enjoyed my son's blood and your card was just great. In case you can't tell, I'm being sarcastic. You stink! You are a senile, buck-toothed old mummy with bony girl-arms, and you smell like an elephant's butt.
* StronglyWordedLetter: Homer's angry letter to Mr Burns.
* UngratefulBastard: Homer believes Burns is one for only sending a thank you card after Bart's blood saved his life.
* VengeanceFeelsEmpty: Mr Burns notes that his revenge on Homer left him empty.
* WhyDontYouJustShootHim: Subverted by Burns.
-->"I could crush him like an ant, but, no. Revenge is a dish best served cold. I'll bide my time until... Oh, what the hell, I'll just crush him like an ant."