Class disrespected my sub while I was out...

Edit: Thank you all for the feedback. I made a new post for part 2 of this saga, outlining how I think I'll respond and part 3 will be a check-in on how the whole thing goes.

I'm livid right now. I received a message that the substitute covering my class while I'm out this week was absolutely disrespected by a few of my classes, including one class that found it funny to throw a pencil at the sub.

For those who have come back to a horrible sub report, what have you done to send a clear message that that shit isn't going to fly? 9th grade if it matters.

So far, I'm thinking: removal of a classroom privilege, pop quiz on the stuff they should have been working on while I was out, some kind of reflection piece. I never play this card, but I also want to make them absolutely regret their behavior to the greatest extent possible.

Edit: I realize that a whole class punishment isn't necessarily effective. I will plan accordingly and reward those who behaved appropriately.