"This is the part where you fall down and bleed-!"
(Killed by arrow to the face)
I made tons of really funny replies to NPCs with this one roleplay I was doing. I was pretending slave traders came on boat to Anvil and they were drugging and kidnapping citizens.
(hyphens are where I clicked to cut off the dialogue.)
Rebania Antus: "You, you must be working for them! No... you're my friend! Hauls-Ropes I'm being targeted!"
Hauls-Ropes-Faster: "You are stupid.-"
Rebania Antus (my character): "I'm not stupid! You see, I was in my house..."
Hauls-Ropes-Faster: "I understand-"
Rebania Antus: "And this man knocked on the door looking for my daughter..."
Hauls-Ropes-Faster: "I understand-"
Rebania Antus: "And he told me we had to come with him, and that we were his property! He WAS a slave driver!"
Hauls-Ropes-Faster: "You are stupid.-"
Rebania Antus: "I'm not stupid!"
Hauls-Ropes-Faster: "You-"
Rebania Antus: "Don't you say it!"
Hauls-Ropes-Faster: "You are stupid!"
Rebania Antus: "I don't need to... to be disgraced in this sort of way! Yo-You're making me feel so terrible, I'm leaving!"
Hauls-Ropes-Faster: "Be seeing you."
Rebania Antus: :stare: "Hauls-Ropes-Faster, you're very mean to me." (I exit dialogue and my daughter enters)
Hauls-Ropes-Faster: "Hello there!"

Rebania Antus: :blink: We're getting out of here Elania.
I've also seen NPCs go bipolar:
"Hail!"
"What's the news from the other parts of Tamriel?"
"You're talking again, and I don't like it." (It was something like that)
"Hmph."