The Simpsons Episode 2.22 Blood Feud

When Mr. Burns gets sick, only a transfusion of Bart's blood, which is a special type, can save him. With the boy's blood coursing through his veins, Mr. Burns is more alive than ever and writes a thank-you note to Bart. Homer is convinced that Burns has not shown his boy enough gratitude and writes his boss a nasty letter. Realizing he's made a mistake, Homer tries repeatedly to stop Burns from getting the note, but can't do it in time. Reading the letter, Mr. Burns vows to ruin Homer's life, but after some strong words from Mr. Smithers, the mogul realizes that he is wrong and shows his gratitude by buying the Simpson family a huge, frightening Olmec Indian statue for their house.