This DM introduced Statler and Waldorf as NPCs in his D&D campaign (which focuses on arena challenges), and they already pissed off one of the players with their comments.

"Well, that fight was different."
"Did you like it?"
"No."
"Then it wasn't different."

After a fumble...
"Well, you gotta give him credit"
"Why's that?"
"He's gonna keep on trying until he succeeds."

"I call that a medium maneuver."
"A medium maneuver?"
"Yeah. It wasn't rare, and it definitly wasn't well done!"

"I wonder if that bard can sing tenor."
"Tenor?"
"Yeah, ten or eleven miles away."

"Hey look, it's a half-elf."
"What's the other half?"
"Not good at fighting, that's for sure."

"So they blew up half the arena"
"At least they blew up the right half."
"Theirs!"

"Look at him run!"
"Yeah, you'd think this was the 40k RPG."
"Why's that?"
"He's a real bolter!"

"Think we should call it a night?"
"Might as well. I certainly wouldn't call it a fight!"

"Just when I thought that fight was terrible something wonderful happened."
"What?"
"It ended."

"Who do you think is the worst combatant?"
"Am I only allowed to choose one?"

"I tried taking medicine before this fight."
"And?"
"Didn't do squat."
"DOHOHOHO-Waldorf? Where'd you go?"