Top definition
The act of one's rectum muscles relaxing so completely that feces flows out without any effort or control devastating all in its path like an avalanche.
ohhhh bro after eating that taco I was hit with a series of shavalanches all night long.

I got so pitted I shavalanched my pants.
by Shiavo August 19, 2009
Get the mug
Get a Shavalanche mug for your mother-in-law Yasemin.