When your going down on a girl who is on her period and you suck some of the blood out of her and lean your head back and bubbles it out of your mouth causing the erruption effect!
Don't really have an example its pretty self explainitory but i wouldn't try the volcano if you and her both dont have a strong stomach.
The result of one fapping for so hard and long that it is blood instead of semen coming out of the penis. It also burns terribly, making it seem hot like a volcano.
Patient: I think i have a little problem...
Doctor: And what might that be??
Patient: Well, I was fapping yesterday, and it was for a long time, and I started cumming blood!
Doctor: Ah, sounds like a volcano to me!! This morphine should do the trick.