Sometimes the PCs in a scene don't really have much to do except observe the actions of NPCs around them. This is when it really pays off to have a good backstory for all of your NPCs.

Or to be a fantastic ad libber.

Transcript

Lando: Hey, clone troopers, I'd just like to say how reasonable you've been in all this.
Clone Trooper 1: Why thank you, sir.
Lando: For an occupying force, you sure are nice guys. It must be a real thankless job.
Clone Trooper 2: It is. But our lives have been improved - and yours can be too - by the Gland Collection Society.
Clone Trooper 1: Its truths are revealed in a wonderful life-changing book.
Clone Trooper 1: We don't know its origins, but it's called The Var—
Lando: Just in time.
{they are ambushed}
Lando: I'll take those weapons. Aide, take them away.
Robot: Lobot, sir.
Clone Trooper 1: Oh. Well, it's still a better reception than we got from Vader.