upside-down volcano 

The act of deficating in an explosive manner. This is usually a diahrea dump resembling a volcanic eruption, upside-down.

I just took the worst shit ever. It was an upside-down volcano.

upside-down volcano by ruppge December 8, 2007

Upside down volcano

A rather graphic representation of a girl on her period.

Man, that girl was bleeding so heavy it looked like an upside down volcano erupting.

Upside down volcano by sullent May 25, 2011

Upside down reverse volcano of snow 

We the man ejaculates into a girls mouth or throat, then the girl( or guy if you are that way) coughs the white oozy cream out of her nose while standing on her head.

Person 1-Dude, I was getin some lettuce, and she pulled an upside down reverse volcano of snow!

Person 2-Umm, right, you wanna have sex in my butthole?

Person 1-Well, you didn't hear a word I said.

Upside down reverse volcano of snow by Charlotte S. August 14, 2006