Mistborn/Funny

When Elend does something stupidly risky in the second book:

Elend: Stay here, wait to see if I get back. If I don't, tell Vin what happened.
Ham: Sure, I'll tell her. Then I'll proceed to remove her daggers from my chest.

After Kelsier comes back from destroying the atium crystals in the Pits of Hathsin:

Ham: Where were you? We've been worried sick that you were out doing something...well, stupid.
Breeze: Actually, we took it for granted that you were doing something stupid. We've just been wondering how stupid this particular event would turn out to be. So, what is it? Did you assassinate the lord prelan? Slaughter dozens of noblemen? Steal the cloak off the Lord Ruler's own back?
Kelsier: I destroyed the Pits of Hathsin.
stunned silence
Breeze: You know, you'd think that by now we'd have learned not to underestimate him.

Vin, on her mysterious acquisition of a ball gown in the last book:

Elend: Seriously, Vin, the army's tailors are good, but there's no way that dress came from materials we had in the camp. Where did you get it?
Vin: It's a mystery. We Mistborn are incredibly mysterious.
Elend: Um... I'm Mistborn, too, Vin. That doesn't make any sense.
Vin: We Mistborn need not make sense. It's beneath us.

- This, incidentally, is a Call Back to Kelsier's use of the same explanation in the first book.
From the same scene, Ham finally finding a captive audience for his philosophical ponderings. It's easy to imagine that only the convenient scene transition prevented a Big No.
When Elend told Vin that killing his fiance, brother and father was a homicidal hat trick.