Binwin Go Down Da Hole

Chris: At the bottom of the stairs, you see that these stairs sort of spill into a chamber supported by four pillars that support the ceiling, and the ceiling is about 10' high. The walls seem to be of loose mortared stone, and the place is dusty and clearly abandoned and has been exposed to the elements for years. What would you like to do?
Scott: Binwin's time to shine!
Chris: Would you like to make a Perception check since you're in the lead?
Scott: Yes, I would like to make a Perception check. Thanks for leading me into that!
...
Scott: Listen. It's clearly safe to move forward, so I'm ready to enter in.
Chris: Okay. Move your figure where you like.
Scott: I'm gonna move...Chris: Okay, stop.
Mike: So, how far can he move? Like, was that his turn? I don't understand what's happening.
Chris: You're not in combat yet, so you can just sort of move wherever you want.
Scott: And then he'll stop me when something happens.
Chris: So, when you get there, you guys on the stairs see him moving cautiously through the room, and then he disappears through the floor.
Jerry: Oh, ****.
Mike: Jim leaves.
Chris: You see this big billowing pile of dust and what appears to be a stone-colored piece of canvas sort of collapse all around him as he plunges into a pit.
Jim: Nice job, Bibwin.
Binwin: It's Binwin!
Chris: And the dwarf makes some sort of noise like, "Oh! HWAAAAH!--boof" as pieces of timber and other things fall on top of his head.
Jerry: But it's a hard sound, not a soft wet sound like it's full of spikes.
Chris: Well, he's in armor, so it's this sort of clattering, crunching noise.
Binwin: I've found a trap!
Jerry: "It's safe now!"
Binwin: My fall-into-holes skill has served me well.
Chris: You take some damage falling into this 10' deep pit, and you basically land prone on your face.
Scott: Oh, yikes.
Jerry: I start to consider the "positions open" ad I'm going to post.
Chris: You take 5 points of damage.
Scott: Hm. What's 31-5?
Mike: You have to do math??
Jerry: Some math.
Mike: You did not tell me there would be math.
Jerry: It's a very reasonable amount of math.
Chris: And then, almost immediately, you feel small creatures crawling all over your body, and they sort make sounds like,
(Chris makes a truly impressive rat squeaking sound.)
Jerry: That's incredible!
Binwin: Raaat kiiing! Raaaaaat kiiiiiing!