porcelain trumpet
the low pitch echoing sound which is heard when one expels gas while sitting firmly on the toilet. Most commonly found when the air between blast of fecal matter is released while having diarrhea.
I walked into that bathroom and the dude in the last stall was playing the porcelain trumpet like a pro.
Playing the Porcelain Trumpet
When a person farts loudly before pooing. The noise is amplified by the hollow bowl of the toilet.
After a long night competitive beer drinking, i awoke to my roomate playing the porcelain trumpet.