It's brimstone. We must be getting close.
5 seconds sound clip from the Shrek (2001) movie soundboard.
You can hear this line at 00:29:12 in the Blu-ray version of the movie.
Quote context
[...]
- You know, I think I preferred your humming.
- Man, you gotta warn somebody before you just crack one off. My mouth was open and everything.
- Believe me, Donkey, if it was me, you'd be dead.
- It's brimstone. We must be getting close.
- Sure, it's big enough, but look at the location.
- Remember when you said that ogres have layers?
- Aye.
- Well, I have a bit of a confession to make.
[...]