When you get up in the middle of the night to go to bathroom, you urinate on the porcelain inside the toilet, instead of directly on the water to avoid making that 'sploshing sound.' This is done to avoid waking up your spouse or a roommate.
"I heard you get up last night and go to the bathroom"

"Really? Thats strange, I took a porcelain piss."
by thelol6 December 26, 2011
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