The bowel movement after eating greasy food that is hot, steamy, chunky liquid; erupting like a volcano out of your anus.
Stan: "Hey Carl, you okay? You don't look so good..."
Carl: "Awh man no. I feel like shit, I just ate KFC and now I'm pouring Brown Lava every five minutes!"
Stan: "Ah bro, I know the feeling. I had Taco Bell last week and it did the same to me."
I just experienced an eruption of brown lava in my pants and on the ground!