Shit volcano

May be used to describe a person or object that spews out excesses of crap in verbal or physical form.

Word derives from a combination of the relatively harmless cuss shit and volcano; which until just recently wasn't considered quite as negative a word as it currently is (post Icelandic volcano ash cloud malarkey).

The act of packing an anus with baking soda then topping off with vinegar to create a shitty, bubbly anal volcano. (Mentos and diet coke can be substituted but with somewhat less spectacular results)

A bout of diarrhea that burns so bad that the hair on you asshole gets singed. When your asshole becomes a blowtorch.