So what do you do if the GM of your game is sick, or indisposed, or otherwise can't make it to your regular gaming session?

You can appoint one of the players as a substitute GM! This requires a careful touch, as the substitute GM needs to know enough about the adventure to run something that will make sense when integrated into the overall campaign, but not so much that it reveals important plot information and secrets to the substitute that will spoil the game when he returns to playing a character.

The easy way out is to insert some scenes that really make no sense whatsoever in the context of the actual adventure, and serve merely as filler that might perhaps, at best, make a half-decent video game sequence.

Transcript

Anakin: Hi Pete... where's—
Pete: {GM-style text box, but white instead of yellow} Due to some family emergency or whatever, I'll be taking over as GM for tonight.
Padmé: Cool!
Obi-Wan: He let you fill in?
Pete: Can you suggest anyone with more GMing experience?
Obi-Wan: But—
Pete: Sally, there's not going to be anything for Mace Windu to do in this session, so you should play C-3PO.
Sally: I don't want to! She's lame and boring!
Pete: No, you'll get cool stuff to do. I promise.
Sally: Really?
Pete: Yeah!
Sally: Okay then!
Padmé: And we'll get cool stuff too?
Pete: Yes.
Padmé: Great!
Pete: Oohhhhh, yes...
Obi-Wan: Already being captured and immobilised is starting to look much more pleasant.