You're an NPC with only one line of dialogue

[plastic_window]

Do a barrel roll!

 

[Ranooth]

ERROR!

 

[The_Chief]

"Hey How ya doin' buddy? wait what are you doing with that gun. hey don't point that at me, someone could get hurt. *pulls out bazooka* you wanna mess nigga? cause ill kick yo ass"

 

[Mr. Fister]

"This is the song that never ends
It just goes on and on, my friends...."

 

[IanB.]

"I'm your real father!"

 

[Fraught]

"You are going to self-destruct/get killed by my henchmen, in approximately 20 seconds. Make your time *proceed to laugh like a madman*"

 

[Your once and future Fanboy]

i would want to a npc that would only come out during the "game over" screen, where i'd point, laugh and say "you suck" in a anoying, nasal voice, thereby making me one of the most memorable characters in the game, just like the duck hunt dog.

 

[confernal]

"Your health is low. Do you have any potions or food."

 

[ZonerZ]

"So, you 18 yet?"

 

[minispike47]

Hero!,Hero!,Hero!,Heeero!

Damn that little ***** from Fable 1, she could follow you around too.

I hate that little whore!

 

[Cliff_m85]

So I guess that's how the rutabega mutated rapidly!

 

[CrafterMan]

The fail is strong in this one.

 

[psico666]

"Press 'X' to not die."

 

[hippo24]

War...war never changes.

or

"Hello Mr.Freeman"

 

[RAWKSTAR]

GOD I FUCKING LOVE THIS CUSTARD!

 

[psico666]

I'm so sorry but this had to be done.
I would say;

"Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you"

 

[Magnuscell]

"Pressing any button at this point may result in instantaneous death; Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light."

 

[johnman]

"Do a barrel roll!"

 

[Overlord_Dave]

"Weary traveller, if you remember but one thing before you murder me and steal my clothes, let it be this:

beware the 172nd step."

That'll artificially extend the playtime somewhat. And improve the player's step counting skills.