6 All the McBain clips in the series can be combined into a single movie.

The character McBain is a movie action hero in the show played by Rainier Wolfcaste. He is a parody of Arnold Schwarzenegger’s height, strength, Austrian accent and limited emotional expression, and Bruce Willis’ sarcasm. The name McBain is a play on the name of Bruce Willis’ character John McClane in the Die Hard movie series.(source)

7 Paul McCartney agreed to appear on the episode “Lisa the Vegetarian” with a request that Lisa remained a vegetarian in all subsequent episodes. The Simpsons staff agreed and kept their promise, resulting in one of the few permanent character changes in the show. 

Since Paul McCartney was the only living member who hadn’t appeared on the show after its creation, the staff thought to pitch him in for the episode in which Lisa becomes a vegetarian. His wife Linda was also recruited for the episode as a guest star and since they are both vegetarians the writers felt it would make an attractive story. The changes made to the characters in the show are not usually permanent. Lisa’s change to vegetarianism was one of the exceptions and she didn’t revert back to eating meat in the next episode.(source)

8 Homer’s trademark expression “D’oh!” was added to Oxford English Dictionary. It was created by the voice actor Dan Castellaneta when Matt Groening asked him to find a sound for Homer’s “annoyed grunt”.

9 Bart’s anonymous prank calls to Moe were inspired by “The Tube Bar Recordings”, tapes of actual prank calls to Louis ‘Red’ Deutsch, a New Jersey bartender famous for his violent temper whom the pranksters saw beating one of his customers for not drinking fast enough. 

10 The telephone number at Moe’s Tavern is 764-8437, or SMITHERS, which was revealed in the episode “Homer the Smithers” when Mr. Burns tries to call his assistant Waylon Smithers, but does not know his number. So, instead he just dials the letters SMITHERS.