MAL: Watch me. River, do you know what you're doing?
RIVER: Do you?
MAL: Pffft. This is what I do.
Joss Whedon: Yeah, baby. This is what I do.
This came across a Browncoat list today:
http://www.swartzer.com/writing/serenity2000.php but be warned, VERY SPOILERY.