To shit oneself, especially if scared
Two bounty hunters are patrolling near a swamp and are startled by a giant scorpion-like creature, which they then kill. Says one to the other "I really dropped some mud there". Attribution: from movie Riddick, 2013, roughly quoted. To drop some mud, i.e. shit oneself from fear.
מאת Carl Davidson 8 בספטמבר, 2013