My favourite quotes in T2 are:
In a conversation between two mechanists, one says angrily:
"A pox upon it!". I found it very funny, and now I say so when angry or annoyed.

One guard said:
"New boots. Gonna take me a week to break in the cursed things. And until then I'll be walking like someone's grandma"

Lady guard and one tortured guy:
- You, guys, can't treat me like this! I'm a veteran!
- Yeah, bet that's where you've learned to pickpocket so well.

And a prisoner:
- They've put me here because I was urinating in the street. Now I ask you - is that fair?

I also like Hammers' and Mechanists' prayers like "Vigilance is our shield..."
"Here at last the man with a hand of a general and a heart of a poet..." they are sticky and I often find myself quietly reciting them

And good old Benny! He is always funny!

I’ve spent the past four months transcribing all of the letters, books, and verbiage from Thief I and II to a database reference. In all of the Nobel Guards conversations I've heard I think none are as funny as the taunting argument between Master Willey and Lady Van Vernon’s guards.