Quickly, make up a random plot twist!

[Emilox The Great]

But then it turned out you DID pay the phone bill!
The bad guy is actually your father AND your daughter!
The cable guy was actually the mailman!!!

 

[zombiejoe]

"The antagonist IS made of broccali!"

"You are your own great great great great great grandmother! Even though your a boy!!"

"Creepers? They look like creepers to you?"

Ok, that last one is actually pretty awesome.

 

[retterkl]

Luke is Darth Vader's father.

 

[Celtic_Kerr]

Question (sorta) is in the title!

"Your son isn't in the house, because YOUR SON IS THE HOUSE"

"Your spinal cord has been plotting to overthrow the french this entire time!"

The villain's brother's nephew's daughter's aunt's father was the bad guy all along!

The murder weapon was actually a whisk, and was only made to look like a Japanese Katana!!!

 

[rtbailey]

It was Yooooooooooooooooooooooooooooooooooooooooooou!
Or was it...?

 

[Daverson]

Spontaneous Alien Invasion!

Imagine how much better any movie would be if Aliens invaded in the third act through with no foreshadowing. Even movies that are already about alien invasions - of course, in this situation, the Alien invasion would be subject to another Alien invasion.

Also, for fun:
DC - 42 essential 3rd act twists [http://dresdencodak.com/2009/05/11/42-essential-3rd-act-twists/]

 

[Not G. Ivingname]

Snip

THAT BUNNY IS REALLY A DRAGON!

 

[Shoggoth2588]

It was RUSSIANS THE ENTIRE TIME!

 

[Yopaz]

[insert generic middle eastern country here] invades America!

That's the main plot, not a plot twist.

It turns out the main character is the evil guy and has been gathering up a party to kill the "villain" who's really the good guy who's just dreaming and everything that's happening will be destroyed when he wakes up.

 

[GeneWard]

The secret ingredient...
IS PEOPLE!

 

[Sallix]

Turns out that that giant brown monster of intergalactic doom, bring death to countless civilizations spanning the entire known and unknown universe, was actually in fact red.

 

[UltraDeth]

Your hat is on fire! And your cousin is pregnant with YOUR CHILD!!!!!!

 

[Communist partisan]

But... I KILLED YOU!

 

[Nickthequick]

The true meaning of christmas wasn't inside you all along, but rather it was in the spirit of gift getting.

 

[The Rockerfly]

no you see i was born inside you. Your my mommy. my real da is mr.T

Well now this is a real plot, you were my sperm which I impregnated someone then the child of that became a machine who went back in time inside of me, changing my gender and making you black

wut

 

[Jakub324]

You realised you were a paedophile!

 

[Huttser]

You finally realize that you have gone insane and what you believed was the truth was a lie created by your misconception of the world by your brain and that in actuality you are the villain and the person you thought was the villain was actually the hero.

 

[Prof. Monkeypox]

The greatest monster of the animal kingdom was MAN ALL ALONG.
-Futurama is awesome

 

[[.redacted]]

It's not a clever film, you're actually just watching the sequel to a really stupid one.

 

[Rayne870]

Question (sorta) is in the title!

"Your son isn't in the house, because YOUR SON IS THE HOUSE"

"Your spinal cord has been plotting to overthrow the french this entire time!"

The French will win that war, even they didn't see that coming.