After 33 seasons on television, The Simpsons has pretty much done it all. There's almost no story they haven't told and some of those stories have been told multiple times. Once a show starts closing in on thousands of episodes, it becomes increasingly difficult to not retread well-trodden ground.

RELATED: Archer: 5 Times Drinking Got Sterling Into Trouble (& 5 Times It Saved The Day)

On top of that, the series has taken some serious twists and turns over the years. And there have been more than a few of them that no one saw coming. Despite being on TV for so long, The Simpsons still has the ability to surprise its fans with some narrative shockers out of left field.

10 Sideshow Bob Framing Krusty

Sideshow Bob with Krusty and Bart

Way back in Season 1, Sideshow Bob was still Krusty the Clown's sidekick. But that wouldn't last long. In Episode 12, Krusty was arrested for robbing the Kwik-E-Mart and put on trial. This led to Bart and Lisa going on their first detective mission together.

What they found out was that Sideshow Bob framed Krusty so he could take the show over. Keeping in mind that this was in 1990 before fans knew how evil Bob actually would be, this was a massive twist that no one saw coming.

9 Grandpa's Other Families

Herb Powell with The Simpsons

The history of Grandpa Simpson is convoluted, to say the least. When his military history is factored in, things get even more complicated as he's been depicted as serving in the Army, the Navy, the Air Force, and the Marine Corps. He was a busy guy.

RELATED: 10 Ways Futurama Is Better Than The Simpsons

His family history also has a few twists and turns. Originally, Grandpa was depicted as having only one son, Homer. In Season 2, Episode 15, another son named Herb Powell was introduced. Then in Season 15, Episode 4, he threw another curveball at the family when his British daughter popped up.

8 Patti And Selma's Real Hair Color

Patti and Selma reveal their real hair colors

Homer's existence has multiple banes. That's the price of living life the way he does, out loud, drunk, and rarely stopping to think about anything. But Patty and Selma, Marge's sisters, are easily the worst as they hate him and he hates them.

Patty and Selma are chain-smoking twins with similar hair colors. One episode revealed that one twin was actually brunette while the other was blonde. Their hair was just always filled with cigarette ash, giving it a purplish hue. This wasn't a massive shock but it still twisted what fans thought they knew.

7 Krusty's Father Was A Rabbi

Krusty with his Rabbi father

The history of Krusty the Clown was shrouded in mystery. It was well known that he was a popular children's entertainer as well as being a terrible and frequently racist comedian. But anything about his personal life was left hidden.

RELATED: Scooby-Doo & 9 Other Cartoon Characters Who Are Nothing Without Their Signature Snack

In Season 3, Episode 5, fans were shocked when they met Rabbi Hyman Krustofsky. It was a major surprise to discover that Krusty the Clown's estranged father was a devout and humorless Rabbi. While they reconciled before Hyman's death, this one caught fans off-guard.

6 Only Simpson's Men Are Failures

Secret War Of Lisa Simpsons

Keeping in mind that Maggie still may eclipse her, Lisa is generally regarded as the smartest member of her immediate family. Well, unless Homer ever pulls that Crayon out of his brain, again. But until that happens, Lisa is the resident brainiac.

But in one episode, Lisa was worried she was getting dumber. Grandpa said it was because of the Simpson gene that would make her stupider over time. Homer disproved that when he accidentally discovered only Simpson men get stupider. The women are generally smart and successful. Poor Bart.

5 Homer's Middle Name Is Jay

Homer rages at New York

When the series started, the focus was put primarily on Bart. Over time, the breakout star became Homer and the show has never looked back. Homer J. Simpson has been the source of some of the funniest TV moments of the last three decades. He's also been the source of a few mysteries.

RELATED: Wubba Lubba Dub Dub & 9 Other TV Catchphrases That Make No Sense

One of them was Homer's middle name. He only knew the initial but following his mother's past led him to a pair of hippies who made juice. She had left a mural on the wall of Homer which revealed his middle name was actually Jay. It was an extremely Homer moment.

4 Principal Skinner Isn't Principal Skinner

Principal Skinner holding a red pen while talking into a mic in The Simpsons.

When a show has been on the air as long as The Simpsons, there are bound to be a few plot lines the producers would rather forget. One of them involved a major twist surrounding Principal Seymour Skinner, specifically that he wasn't Principal Seymour Skinner.

It turned out the real one was believed to have died in Vietnam. Armin Tamzarian took his place when he went to break the news to Mrs. Skinner. The real Seymour was a POW and returned, revealing the truth. But the residents collectively decided they like Armin better so he remained as Seymour Skinner.

3 Homer's Mother Was Alive

Mona Simpson says goodbye to Homer

For the first few seasons, fans of the show believed that Homer's mother had died when he was very young. She was shown a bit during flashbacks but the main focus was on Abe Simpson who had raised Homer as a single father.

RELATED: 10 Movies Based On TV Shows Released While The Show Was Still On The Air

Then in Season 7, Episode 8, Mona Simpson suddenly returned. It was revealed that she had been on the run from crimes committed decades earlier. Homer had faked his death in this episode, drawing her out of hiding and utterly blowing his mind.

2 Maggie Shot Mr. Burns

The Simpsons - Maggie on Santa's Little Helper

To date, there has been only one two-part episode in the series. It was a cliffhanger that started in Season 6, Episode 25, and finished in Season 7, Episode 1. The crux of the story was the investigation of who shot Mr. Burns, which Chief Wiggum absolutely bungled.

While pretty much everyone in Springfield had a motive, it was Maggie Simpson who did it. She accidentally shot him with his own gun when he tried to steal candy from her. Since then, Maggie has shot several more people so the "accidental" nature of the Burns shooting is dubious at best.

1 The Death Of Maude Flanders

Ned and Maude's wedding photo

No one saw this one coming at all. While attending a race at the Springfield Speedway, Homer wanted a free t-shirt so he lobbied the women with the t-shirt cannons quite heavily. They unleashed a barrage that missed Homer and struck Maude Flanders, sending her tumbling to her death.

The character was killed off when the actress who voiced Maude requested a raise to pay for travel costs. Producers initially recast Maude, then decided to get rid of the character entirely to open up opportunities for new storylines with Ned Flanders.

NEXT: 10 Animated Shows That Make Great Songs