When I have to take a dump particularly much, or the dump that I take is remarkable somehow, the word that usually comes to mind is "steamy", as in, man that was a big, steamy dump. Probably it comes from here. I don't think I really said it before I saw this clip years ago, but I definitely use it a lot now. Usually "big" or "meaty" might also be involved. No, just big, not meaty.
But dumps aren't steamy unless they're in the snow or something. So what gives? Where am I getting this from?
There's something kind of empowering, after you've taken a heinous crap that you wanted very badly to get out of your body, to think of it steaming like it came from hell or something. Maybe that's where it comes from. Smelly and steamy are not unrelated in a cartoon vision of smell having little steam lines.
One thing to notes is that dumps can be steamy, but not poops or shits. Maybe turds. But steamy & dump just go together so well!