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Porcelain Percussion is the bass sound heard outside a bathroom when the occupant is involved in a rear-end explosion. This event usually results in having to clean the bowl before exiting the facilities.
Cathy: Damn Bob, that was some serious Porcelain Percussion!! It almost smells as bad as my fold jam.

Bob: Thanks...if you would have done that, your toilet muffin would have slapped you in the head.
by Nate and Mike February 16, 2007