People who won't stop bragging about their involvement in torture races, i.e. Tough Mudder, Spartan Run, etc.
"Here comes Steve wearing a new race shirt he's going to tell us all about, what a mudder fucker."
by Lenny Laserdisc May 12, 2015
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Guy1: Did you hear Michael completed the Tough Mudder Challenge?

Guy2: Yeah he's a Tough Mudder Fucker.
by XxMayhem6xX February 19, 2012
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