Right, well there are a lot of instances like this in the game, but I thought this one was pretty funny.

Maven black briar tells you in one of the thieves guild quests that she's tight with the dark brotherhood, and she'll sick em on you if you mess with her.

I would propose another reply to that for those who have completed the Dark Brotherhood questline.

"[censored], I AM the Dark Brotherhood!"

There are a lot of instances like this, and threads about them too. This is just one that struck me as particularly funny, like I said before.

I also noticed this when I went to kill Karliah but the thieves guild wont have the Dark Brotherhood kill people.

*rageface* I am the Dark Brotherhood!

And I AM the Emperor's illigitimate son/daughter! No one will take you seriously.