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1.
An unfortunate occurrence during ass wiping where a finger pokes through the paper, and touches poop.

A mud foul is typically the result of hurried wiping and/or cheap toilet paper.

Due to direct contact, the malodor will linger on the affected area despite repeated washings.
I had to pull over to shit at the gas station, and committed a serious mud foul when my finger poked through that cheap-ass toilet paper. My finger stank for days.
by Skip Bumphrey August 23, 2008